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Merge pull request #9 from eugenp/master

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update with origin
This commit is contained in:
Maiklins
2019-09-09 10:57:44 +02:00
committed by GitHub
parent db85c8f275
commit 621491f8db
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core-java-modules/core-java-8/.gitignore
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*.class
0.*
#folders#
/target
/neoDb*
/data
/src/main/webapp/WEB-INF/classes
*/META-INF/*
.resourceCache
# Packaged files #
*.jar
*.war
*.ear
# Files generated by integration tests
*.txt
backup-pom.xml
/bin/
/temp
#IntelliJ specific
.idea/
*.iml
core-java-modules/core-java-8/README.md
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=========
## Core Java 8 Cookbooks and Examples
### Relevant Articles:
- [Guide to Java 8’s Collectors](http://www.baeldung.com/java-8-collectors)
- [New Features in Java 8](http://www.baeldung.com/java-8-new-features)
- [The Double Colon Operator in Java 8](http://www.baeldung.com/java-8-double-colon-operator)
- [Guide to Java 8 groupingBy Collector](http://www.baeldung.com/java-groupingby-collector)
- [Strategy Design Pattern in Java 8](http://www.baeldung.com/java-strategy-pattern)
- [Guide to Java 8 Comparator.comparing()](http://www.baeldung.com/java-8-comparator-comparing)
- [Guide To Java 8 Optional](http://www.baeldung.com/java-optional)
- [Guide to the Java 8 forEach](http://www.baeldung.com/foreach-java)
- [The Difference Between map() and flatMap()](http://www.baeldung.com/java-difference-map-and-flatmap)
- [Static and Default Methods in Interfaces in Java](http://www.baeldung.com/java-static-default-methods)
- [Efficient Word Frequency Calculator in Java](http://www.baeldung.com/java-word-frequency)
- [Introduction to Spliterator in Java](http://www.baeldung.com/java-spliterator)
- [Java 8 Math New Methods](http://www.baeldung.com/java-8-math)
- [Overview of Java Built-in Annotations](http://www.baeldung.com/java-default-annotations)
- [Finding Min/Max in an Array with Java](http://www.baeldung.com/java-array-min-max)
- [Internationalization and Localization in Java 8](http://www.baeldung.com/java-8-localization)
- [Java Optional – orElse() vs orElseGet()](http://www.baeldung.com/java-optional-or-else-vs-or-else-get)
- [Java 8 Unsigned Arithmetic Support](http://www.baeldung.com/java-unsigned-arithmetic)
- [Generalized Target-Type Inference in Java](http://www.baeldung.com/java-generalized-target-type-inference)
- [Overriding System Time for Testing in Java](http://www.baeldung.com/java-override-system-time)
- [Set the Time Zone of a Date in Java](https://www.baeldung.com/java-set-date-time-zone)
- [An Overview of Regular Expressions Performance in Java](https://www.baeldung.com/java-regex-performance)
- [Java Primitives versus Objects](https://www.baeldung.com/java-primitives-vs-objects)
- [How to Use if/else Logic in Java 8 Streams](https://www.baeldung.com/java-8-streams-if-else-logic)
- [How to Replace Many if Statements in Java](https://www.baeldung.com/java-replace-if-statements)
- [Java @Override Annotation](https://www.baeldung.com/java-override)
- [Java @SuppressWarnings Annotation](https://www.baeldung.com/java-suppresswarnings)
- [Java @SafeVarargs Annotation](https://www.baeldung.com/java-safevarargs)
- [Java @Deprecated Annotation](https://www.baeldung.com/java-deprecated)
- [Java 8 Predicate Chain](https://www.baeldung.com/java-predicate-chain)
- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
- [The Difference Between Collection.stream().forEach() and Collection.forEach()](https://www.baeldung.com/java-collection-stream-foreach)
core-java-modules/core-java-8/pom.xml
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.baeldung</groupId>
<artifactId>core-java-8</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-8</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>${commons-collections4.version}</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>${commons-io.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-math3</artifactId>
<version>${commons-math3.version}</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>${commons-codec.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<!-- test scoped -->
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.jayway.awaitility</groupId>
<artifactId>awaitility</artifactId>
<version>${avaitility.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>${jmh-core.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>${jmh-generator.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-bytecode</artifactId>
<version>${jmh-generator.version}</version>
</dependency>
<dependency>
<groupId>com.codepoetics</groupId>
<artifactId>protonpack</artifactId>
<version>${protonpack.version}</version>
</dependency>
<dependency>
<groupId>io.vavr</groupId>
<artifactId>vavr</artifactId>
<version>${vavr.version}</version>
</dependency>
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>${joda.version}</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>${asspectj.version}</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>${asspectj.version}</version>
</dependency>
<dependency>
<groupId>org.powermock</groupId>
<artifactId>powermock-module-junit4</artifactId>
<version>${powermock.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.powermock</groupId>
<artifactId>powermock-api-mockito2</artifactId>
<version>${powermock.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.jmockit</groupId>
<artifactId>jmockit</artifactId>
<version>${jmockit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>core-java-8</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>${spring-boot-maven-plugin.version}</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
<configuration>
<classifier>spring-boot</classifier>
<mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>${maven-surefire-plugin.version}</version>
<configuration>
<argLine>
-javaagent:${settings.localRepository}/org/jmockit/jmockit/${jmockit.version}/jmockit-${jmockit.version}.jar
</argLine>
<disableXmlReport>true</disableXmlReport>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<!-- util -->
<commons-math3.version>3.6.1</commons-math3.version>
<commons-collections4.version>4.1</commons-collections4.version>
<collections-generic.version>4.01</collections-generic.version>
<commons-codec.version>1.10</commons-codec.version>
<vavr.version>0.9.0</vavr.version>
<protonpack.version>1.13</protonpack.version>
<joda.version>2.10</joda.version>
<!-- testing -->
<assertj.version>3.6.1</assertj.version>
<asspectj.version>1.8.9</asspectj.version>
<powermock.version>2.0.0-RC.4</powermock.version>
<jmockit.version>1.44</jmockit.version>
<avaitility.version>1.7.0</avaitility.version>
<jmh-core.version>1.19</jmh-core.version>
<jmh-generator.version>1.19</jmh-generator.version>
<spring-boot-maven-plugin.version>2.0.4.RELEASE</spring-boot-maven-plugin.version>
<!-- plugins -->
<maven-surefire-plugin.version>2.22.1</maven-surefire-plugin.version>
</properties>
</project>
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/ClassWithAnnotation.java
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package com.baeldung.annotations;
@Deprecated
class ClassWithAnnotation {
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/ClassWithDeprecatedMethod.java
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package com.baeldung.annotations;
class ClassWithDeprecatedMethod {
@Deprecated
static void deprecatedMethod() {
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/ClassWithSafeVarargs.java
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package com.baeldung.annotations;
class ClassWithSafeVarargs<T> {
@SafeVarargs
final void iterateOverVarargs(T... args) {
for (T x : args) {
// do stuff with x
}
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/ClassWithSuppressWarnings.java
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package com.baeldung.annotations;
class ClassWithSuppressWarnings {
@SuppressWarnings("deprecation")
void useDeprecatedMethod() {
ClassWithDeprecatedMethod.deprecatedMethod(); // no warning is generated here
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/IntConsumer.java
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package com.baeldung.annotations;
@FunctionalInterface
interface IntConsumer {
void accept(Integer number);
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/Interval.java
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package com.baeldung.annotations;
import java.lang.annotation.Repeatable;
@Repeatable(Intervals.class)
@interface Interval {
int hour() default 1;
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/IntervalUsage.java
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package com.baeldung.annotations;
public class IntervalUsage {
@Interval(hour = 17)
@Interval(hour = 13)
void doPeriodicCleanup() {
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/Intervals.java
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package com.baeldung.annotations;
@interface Intervals {
Interval[] value();
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/MyAnnotation.java
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package com.baeldung.annotations;
import java.lang.annotation.*;
@Inherited
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.LOCAL_VARIABLE, ElementType.FIELD})
@interface MyAnnotation {
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/MyAnnotationTarget.java
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package com.baeldung.annotations;
class MyAnnotationTarget {
// this is OK
@MyAnnotation
String someField;
// @MyAnnotation <- this is invalid usage!
void doSomething() {
// this also works
@MyAnnotation
String localVariable;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/MyOperation.java
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package com.baeldung.annotations;
interface MyOperation {
void perform();
}
core-java-modules/core-java-8/src/main/java/com/baeldung/annotations/MyOperationImpl.java
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package com.baeldung.annotations;
class MyOperationImpl implements MyOperation {
@Override
public void perform() {
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/aspect/ChangeCallsToCurrentTimeInMillisMethod.aj
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package com.baeldung.aspect;
public aspect ChangeCallsToCurrentTimeInMillisMethod {
long around():
call(public static native long java.lang.System.currentTimeMillis())
&& within(user.code.base.pckg.*) {
return 0;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/customannotations/Init.java
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package com.baeldung.customannotations;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
@Retention(RUNTIME)
@Target(METHOD)
public @interface Init {
}
core-java-modules/core-java-8/src/main/java/com/baeldung/customannotations/JsonElement.java
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package com.baeldung.customannotations;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
@Retention(RUNTIME)
@Target({ FIELD })
public @interface JsonElement {
public String key() default "";
}
core-java-modules/core-java-8/src/main/java/com/baeldung/customannotations/JsonSerializable.java
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package com.baeldung.customannotations;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
@Retention(RUNTIME)
@Target(TYPE)
public @interface JsonSerializable {
}
core-java-modules/core-java-8/src/main/java/com/baeldung/customannotations/JsonSerializationException.java
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package com.baeldung.customannotations;
public class JsonSerializationException extends RuntimeException {
private static final long serialVersionUID = 1L;
public JsonSerializationException(String message) {
super(message);
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/customannotations/ObjectToJsonConverter.java
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package com.baeldung.customannotations;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.stream.Collectors;
public class ObjectToJsonConverter {
public String convertToJson(Object object) throws JsonSerializationException {
try {
checkIfSerializable(object);
initializeObject(object);
return getJsonString(object);
} catch (Exception e) {
throw new JsonSerializationException(e.getMessage());
}
}
private void checkIfSerializable(Object object) {
if (Objects.isNull(object)) {
throw new JsonSerializationException("Can't serialize a null object");
}
Class<?> clazz = object.getClass();
if (!clazz.isAnnotationPresent(JsonSerializable.class)) {
throw new JsonSerializationException("The class " + clazz.getSimpleName() + " is not annotated with JsonSerializable");
}
}
private void initializeObject(Object object) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
Class<?> clazz = object.getClass();
for (Method method : clazz.getDeclaredMethods()) {
if (method.isAnnotationPresent(Init.class)) {
method.setAccessible(true);
method.invoke(object);
}
}
}
private String getJsonString(Object object) throws IllegalArgumentException, IllegalAccessException {
Class<?> clazz = object.getClass();
Map<String, String> jsonElementsMap = new HashMap<>();
for (Field field : clazz.getDeclaredFields()) {
field.setAccessible(true);
if (field.isAnnotationPresent(JsonElement.class)) {
jsonElementsMap.put(getKey(field), (String) field.get(object));
}
}
String jsonString = jsonElementsMap.entrySet()
.stream()
.map(entry -> "\"" + entry.getKey() + "\":\"" + entry.getValue() + "\"")
.collect(Collectors.joining(","));
return "{" + jsonString + "}";
}
private String getKey(Field field) {
String value = field.getAnnotation(JsonElement.class)
.key();
return value.isEmpty() ? field.getName() : value;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/customannotations/Person.java
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package com.baeldung.customannotations;
@JsonSerializable
public class Person {
@JsonElement
private String firstName;
@JsonElement
private String lastName;
@JsonElement(key = "personAge")
private String age;
private String address;
public Person(String firstName, String lastName) {
super();
this.firstName = firstName;
this.lastName = lastName;
}
public Person(String firstName, String lastName, String age) {
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
}
@Init
private void initNames() {
this.firstName = this.firstName.substring(0, 1)
.toUpperCase() + this.firstName.substring(1);
this.lastName = this.lastName.substring(0, 1)
.toUpperCase() + this.lastName.substring(1);
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/application/Application.java
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package com.baeldung.defaultstaticinterfacemethods.application;
import com.baeldung.defaultstaticinterfacemethods.model.Car;
import com.baeldung.defaultstaticinterfacemethods.model.Vehicle;
public class Application {
public static void main(String[] args) {
Vehicle car = new Car("BMW");
System.out.println(car.getBrand());
System.out.println(car.speedUp());
System.out.println(car.slowDown());
System.out.println(car.turnAlarmOn());
System.out.println(car.turnAlarmOff());
System.out.println(Vehicle.getHorsePower(2500, 480));
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Alarm.java
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package com.baeldung.defaultstaticinterfacemethods.model;
public interface Alarm {
default String turnAlarmOn() {
return "Turning the alarm on.";
}
default String turnAlarmOff() {
return "Turning the alarm off.";
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Car.java
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package com.baeldung.defaultstaticinterfacemethods.model;
public class Car implements Vehicle {
private final String brand;
public Car(String brand) {
this.brand = brand;
}
@Override
public String getBrand() {
return brand;
}
@Override
public String speedUp() {
return "The car is speeding up.";
}
@Override
public String slowDown() {
return "The car is slowing down.";
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Motorbike.java
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package com.baeldung.defaultstaticinterfacemethods.model;
public class Motorbike implements Vehicle {
private final String brand;
public Motorbike(String brand) {
this.brand = brand;
}
@Override
public String getBrand() {
return brand;
}
@Override
public String speedUp() {
return "The motorbike is speeding up.";
}
@Override
public String slowDown() {
return "The motorbike is slowing down.";
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/MultiAlarmCar.java
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package com.baeldung.defaultstaticinterfacemethods.model;
public class MultiAlarmCar implements Vehicle, Alarm {
private final String brand;
public MultiAlarmCar(String brand) {
this.brand = brand;
}
@Override
public String getBrand() {
return brand;
}
@Override
public String speedUp() {
return "The motorbike is speeding up.";
}
@Override
public String slowDown() {
return "The mootorbike is slowing down.";
}
@Override
public String turnAlarmOn() {
return Vehicle.super.turnAlarmOn() + " " + Alarm.super.turnAlarmOn();
}
@Override
public String turnAlarmOff() {
return Vehicle.super.turnAlarmOff() + " " + Alarm.super.turnAlarmOff();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Vehicle.java
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package com.baeldung.defaultstaticinterfacemethods.model;
public interface Vehicle {
String getBrand();
String speedUp();
String slowDown();
default String turnAlarmOn() {
return "Turning the vehice alarm on.";
}
default String turnAlarmOff() {
return "Turning the vehicle alarm off.";
}
static int getHorsePower(int rpm, int torque) {
return (rpm * torque) / 5252;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/doublecolon/Computer.java
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package com.baeldung.doublecolon;
public class Computer {
private Integer age;
private String color;
private Integer healty;
Computer(final int age, final String color) {
this.age = age;
this.color = color;
}
Computer(final Integer age, final String color, final Integer healty) {
this.age = age;
this.color = color;
this.healty = healty;
}
public Computer() {
}
public Integer getAge() {
return age;
}
public void setAge(final Integer age) {
this.age = age;
}
String getColor() {
return color;
}
public void setColor(final String color) {
this.color = color;
}
Integer getHealty() {
return healty;
}
void setHealty(final Integer healty) {
this.healty = healty;
}
public void turnOnPc() {
System.out.println("Computer turned on");
}
public void turnOffPc() {
System.out.println("Computer turned off");
}
public Double calculateValue(Double initialValue) {
return initialValue / 1.50;
}
@Override
public String toString() {
return "Computer{" + "age=" + age + ", color='" + color + '\'' + ", healty=" + healty + '}';
}
@Override
public boolean equals(final Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
final Computer computer = (Computer) o;
return (age != null ? age.equals(computer.age) : computer.age == null) && (color != null ? color.equals(computer.color) : computer.color == null);
}
@Override
public int hashCode() {
int result = age != null ? age.hashCode() : 0;
result = 31 * result + (color != null ? color.hashCode() : 0);
return result;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/doublecolon/ComputerUtils.java
+27
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package com.baeldung.doublecolon;
import com.baeldung.doublecolon.function.ComputerPredicate;
import java.util.ArrayList;
import java.util.List;
public class ComputerUtils {
static final ComputerPredicate after2010Predicate = (c) -> (c.getAge() > 2010);
static final ComputerPredicate blackPredicate = (c) -> "black".equals(c.getColor());
public static List<Computer> filter(final List<Computer> inventory, final ComputerPredicate p) {
final List<Computer> result = new ArrayList<>();
inventory.stream().filter(p::filter).forEach(result::add);
return result;
}
static void repair(final Computer computer) {
if (computer.getHealty() < 50) {
computer.setHealty(100);
}
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/doublecolon/MacbookPro.java
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package com.baeldung.doublecolon;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.function.Function;
public class MacbookPro extends Computer {
private static final Logger LOG = LoggerFactory.getLogger(MacbookPro.class);
public MacbookPro(int age, String color) {
super(age, color);
}
MacbookPro(Integer age, String color, Integer healty) {
super(age, color, healty);
}
@Override
public void turnOnPc() {
LOG.debug("MacbookPro turned on");
}
@Override
public void turnOffPc() {
LOG.debug("MacbookPro turned off");
}
@Override
public Double calculateValue(Double initialValue) {
Function<Double, Double> function = super::calculateValue;
final Double pcValue = function.apply(initialValue);
LOG.debug("First value is:" + pcValue);
return pcValue + (initialValue / 10);
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/doublecolon/function/ComputerPredicate.java
+10
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package com.baeldung.doublecolon.function;
import com.baeldung.doublecolon.Computer;
@FunctionalInterface
public interface ComputerPredicate {
boolean filter(Computer c);
}
core-java-modules/core-java-8/src/main/java/com/baeldung/doublecolon/function/TriFunction.java
+15
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package com.baeldung.doublecolon.function;
import java.util.Objects;
import java.util.function.Function;
@FunctionalInterface
public interface TriFunction<A, B, C, R> {
R apply(A a, B b, C c);
default <V> TriFunction<A, B, C, V> andThen(final Function<? super R, ? extends V> after) {
Objects.requireNonNull(after);
return (final A a, final B b, final C c) -> after.apply(apply(a, b, c));
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/Address.java
+14
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package com.baeldung.java_8_features;
public class Address {
private String street;
public String getStreet() {
return street;
}
public void setStreet(String street) {
this.street = street;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/CustomException.java
+4
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package com.baeldung.java_8_features;
public class CustomException extends RuntimeException {
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/OptionalAddress.java
+16
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package com.baeldung.java_8_features;
import java.util.Optional;
public class OptionalAddress {
private String street;
public Optional<String> getStreet() {
return Optional.ofNullable(street);
}
public void setStreet(String street) {
this.street = street;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/OptionalUser.java
+16
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package com.baeldung.java_8_features;
import java.util.Optional;
public class OptionalUser {
private OptionalAddress address;
public Optional<OptionalAddress> getAddress() {
return Optional.of(address);
}
public void setAddress(OptionalAddress address) {
this.address = address;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/User.java
+40
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package com.baeldung.java_8_features;
import java.util.Optional;
public class User {
private String name;
private Address address;
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public User() {
}
public User(String name) {
this.name = name;
}
public static boolean isRealUser(User user) {
return true;
}
public String getOrThrow() {
String value = null;
Optional<String> valueOpt = Optional.ofNullable(value);
String result = valueOpt.orElseThrow(CustomException::new).toUpperCase();
return result;
}
public boolean isLegalName(String name) {
return name.length() > 3 && name.length() < 16;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/Vehicle.java
+18
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package com.baeldung.java_8_features;
public interface Vehicle {
void moveTo(long altitude, long longitude);
static String producer() {
return "N&F Vehicles";
}
default long[] startPosition() {
return new long[] { 23, 15 };
}
default String getOverview() {
return "ATV made by " + producer();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/VehicleImpl.java
+9
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package com.baeldung.java_8_features;
public class VehicleImpl implements Vehicle {
@Override
public void moveTo(long altitude, long longitude) {
// do nothing
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/BlogPost.java
+36
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package com.baeldung.java_8_features.groupingby;
public class BlogPost {
private String title;
private String author;
private BlogPostType type;
private int likes;
public BlogPost(String title, String author, BlogPostType type, int likes) {
this.title = title;
this.author = author;
this.type = type;
this.likes = likes;
}
public String getTitle() {
return title;
}
public String getAuthor() {
return author;
}
public BlogPostType getType() {
return type;
}
public int getLikes() {
return likes;
}
@Override
public String toString() {
return "BlogPost{" + "title='" + title + '\'' + ", type=" + type + ", likes=" + likes + '}';
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/BlogPostType.java
+5
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package com.baeldung.java_8_features.groupingby;
public enum BlogPostType {
NEWS, REVIEW, GUIDE
}
core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/Tuple.java
+34
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package com.baeldung.java_8_features.groupingby;
public class Tuple {
private BlogPostType type;
private String author;
public Tuple(BlogPostType type, String author) {
super();
this.type = type;
this.author = author;
}
public BlogPostType getType() {
return type;
}
public void setType(BlogPostType type) {
this.type = type;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
@Override
public String toString() {
return "Tuple [type=" + type + ", author=" + author + ", getType()=" + getType() + ", getAuthor()=" + getAuthor() + ", getClass()=" + getClass() + ", hashCode()=" + hashCode() + ", toString()=" + super.toString() + "]";
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/nullsafecollectionstreams/NullSafeCollectionStreamsUsingCommonsEmptyIfNull.java
+19
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package com.baeldung.nullsafecollectionstreams;
import java.util.Collection;
import java.util.stream.Stream;
import static org.apache.commons.collections4.CollectionUtils.emptyIfNull;
public class NullSafeCollectionStreamsUsingCommonsEmptyIfNull {
/**
* This method shows how to make a null safe stream from a collection through the use of
* emptyIfNull() method from Apache Commons CollectionUtils library
*
* @param collection The collection that is to be converted into a stream
* @return The stream that has been created from the collection or an empty stream if the collection is null
*/
public Stream<String> collectionAsStream(Collection<String> collection) {
return emptyIfNull(collection).stream();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/nullsafecollectionstreams/NullSafeCollectionStreamsUsingJava8OptionalContainer.java
+21
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package com.baeldung.nullsafecollectionstreams;
import java.util.Collection;
import java.util.Optional;
import java.util.stream.Stream;
public class NullSafeCollectionStreamsUsingJava8OptionalContainer {
/**
* This method shows how to make a null safe stream from a collection through the use of
* Java SE 8’s Optional Container
*
* @param collection The collection that is to be converted into a stream
* @return The stream that has been created from the collection or an empty stream if the collection is null
*/
public Stream<String> collectionAsStream(Collection<String> collection) {
return Optional.ofNullable(collection)
.map(Collection::stream)
.orElseGet(Stream::empty);
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/nullsafecollectionstreams/NullSafeCollectionStreamsUsingNullDereferenceCheck.java
+20
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package com.baeldung.nullsafecollectionstreams;
import java.util.Collection;
import java.util.stream.Stream;
public class NullSafeCollectionStreamsUsingNullDereferenceCheck {
/**
* This method shows how to make a null safe stream from a collection through the use of a check
* to prevent null dereferences
*
* @param collection The collection that is to be converted into a stream
* @return The stream that has been created from the collection or an empty stream if the collection is null
*/
public Stream<String> collectionAsStream(Collection<String> collection) {
return collection == null ? Stream.empty() : collection.stream();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/optional/Modem.java
+13
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package com.baeldung.optional;
public class Modem {
private Double price;
public Modem(Double price) {
this.price = price;
}
public Double getPrice() {
return price;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/optional/OrElseAndOrElseGet.java
+34
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package com.baeldung.optional;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.Random;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class OrElseAndOrElseGet {
public static List<String> names = Arrays.asList("John", "Jones", "Kelly", "Cristina", "Raven");
private static final Logger LOG = LoggerFactory.getLogger(OrElseAndOrElseGet.class);
public String getRandomName() {
LOG.info("getRandomName() method - start");
Random random = new Random();
int index = random.nextInt(5);
LOG.info("getRandomName() method - end");
return names.get(index);
}
public String getNameUsingOrElse(String name) {
return Optional.ofNullable(name)
.orElse(getRandomName());
}
public String getNameUsingOrElseGet(String name) {
return Optional.ofNullable(name)
.orElseGet(() -> getRandomName());
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/optional/OrElseAndOrElseGetBenchmarkRunner.java
+37
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package com.baeldung.optional;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.runner.RunnerException;
@Fork(1)
@State(Scope.Benchmark)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class OrElseAndOrElseGetBenchmarkRunner {
private OrElseAndOrElseGet orElsevsOrElseGet = new OrElseAndOrElseGet();
public static void main(String[] args) throws RunnerException, IOException {
org.openjdk.jmh.Main.main(args);
}
@Benchmark
public String orElseBenchmark() {
return orElsevsOrElseGet.getNameUsingOrElse("baeldung");
}
@Benchmark
public String orElseGetBenchmark() {
return orElsevsOrElseGet.getNameUsingOrElseGet("baeldung");
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/optional/Person.java
+39
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package com.baeldung.optional;
import java.util.Optional;
public class Person {
private String name;
private int age;
private String password;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public Optional<String> getName() {
return Optional.ofNullable(name);
}
public void setName(String name) {
this.name = name;
}
public Optional<Integer> getAge() {
return Optional.ofNullable(age);
}
public void setAge(int age) {
this.age = age;
}
public void setPassword(String password) {
this.password = password;
}
public Optional<String> getPassword() {
return Optional.ofNullable(password);
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/optional/PersonRepository.java
+9
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package com.baeldung.optional;
public class PersonRepository {
public String findNameById(String id) {
return id == null ? null : "Name";
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/BenchmarkRunner.java
+23
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package com.baeldung.primitive;
public class BenchmarkRunner {
public static void main(String[] args) throws Exception {
new IntPrimitiveLookup().run();
new IntegerWrapperLookup().run();
new FloatPrimitiveLookup().run();
new FloatWrapperLookup().run();
new DoublePrimitiveLookup().run();
new DoubleWrapperLookup().run();
new ShortPrimitiveLookup().run();
new ShortWrapperLookup().run();
new BooleanPrimitiveLookup().run();
new BooleanWrapperLookup().run();
new CharPrimitiveLookup().run();
new CharacterWrapperLookup().run();
new BytePrimitiveLookup().run();
new ByteWrapperLookup().run();
new LongPrimitiveLookup().run();
new LongWrapperLookup().run();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/BooleanPrimitiveLookup.java
+45
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@@ -0,0 +1,45 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class BooleanPrimitiveLookup extends Lookup {
private boolean[] elements;
private final boolean pivot = false;
@Setup
@Override
public void prepare() {
elements = new boolean[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = true;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return BooleanPrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/BooleanWrapperLookup.java
+45
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@@ -0,0 +1,45 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class BooleanWrapperLookup extends Lookup {
private Boolean[] elements;
private final boolean pivot = false;
@Override
@Setup
public void prepare() {
elements = new Boolean[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = true;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Boolean pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return BooleanWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/BytePrimitiveLookup.java
+46
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@@ -0,0 +1,46 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class BytePrimitiveLookup extends Lookup {
private byte[] elements;
private final byte pivot = 2;
@Setup
@Override
public void prepare() {
byte common = 1;
elements = new byte[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return BytePrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/ByteWrapperLookup.java
+46
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@@ -0,0 +1,46 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class ByteWrapperLookup extends Lookup {
private Byte[] elements;
private final byte pivot = 2;
@Override
@Setup
public void prepare() {
byte common = 1;
elements = new Byte[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Byte pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return ByteWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/CharPrimitiveLookup.java
+46
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@@ -0,0 +1,46 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class CharPrimitiveLookup extends Lookup {
private char[] elements;
private final char pivot = 'b';
@Setup
@Override
public void prepare() {
char common = 'a';
elements = new char[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return CharPrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/CharacterWrapperLookup.java
+46
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@@ -0,0 +1,46 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class CharacterWrapperLookup extends Lookup {
private Character[] elements;
private final char pivot = 'b';
@Override
@Setup
public void prepare() {
char common = 'a';
elements = new Character[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Character pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return CharacterWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/DoublePrimitiveLookup.java
+42
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@@ -0,0 +1,42 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class DoublePrimitiveLookup extends Lookup {
private double[] elements;
private final double pivot = 2;
@Setup
@Override
public void prepare() {
double common = 1;
elements = new double[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return DoublePrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/DoubleWrapperLookup.java
+45
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@@ -0,0 +1,45 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class DoubleWrapperLookup extends Lookup {
private Double[] elements;
private final double pivot = 2d;
@Override
@Setup
public void prepare() {
double common = 1;
elements = new Double[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Double pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return DoubleWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/FloatPrimitiveLookup.java
+42
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@@ -0,0 +1,42 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class FloatPrimitiveLookup extends Lookup {
private float[] elements;
private final float pivot = 2;
@Setup
@Override
public void prepare() {
int common = 1;
elements = new float[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return FloatPrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/FloatWrapperLookup.java
+43
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@@ -0,0 +1,43 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class FloatWrapperLookup extends Lookup {
private Float[] elements;
private final float pivot = 2;
@Override
@Setup
public void prepare() {
float common = 1;
elements = new Float[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Float pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return FloatWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/IntPrimitiveLookup.java
+45
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@@ -0,0 +1,45 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class IntPrimitiveLookup extends Lookup {
private int[] elements;
private final int pivot = 2;
@Setup
@Override
public void prepare() {
int common = 1;
elements = new int[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return IntPrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/IntegerWrapperLookup.java
+45
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@@ -0,0 +1,45 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class IntegerWrapperLookup extends Lookup {
private Integer[] elements;
private final int pivot = 2;
@Override
@Setup
public void prepare() {
int common = 1;
elements = new Integer[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Integer pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return IntegerWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/LongPrimitiveLookup.java
+42
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@@ -0,0 +1,42 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class LongPrimitiveLookup extends Lookup {
private long[] elements;
private final long pivot = 2;
@Setup
@Override
public void prepare() {
long common = 1;
elements = new long[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return LongPrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/LongWrapperLookup.java
+45
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@@ -0,0 +1,45 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class LongWrapperLookup extends Lookup{
private Long[] elements;
private final long pivot = 2;
@Override
@Setup
public void prepare() {
long common = 1;
elements = new Long[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Long pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return LongWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/Lookup.java
+56
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@@ -0,0 +1,56 @@
package com.baeldung.primitive;
import org.openjdk.jmh.results.RunResult;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;
import java.util.Collection;
/**
* An abstract class that is to be extended by the classes that
* perform lookup in the arrays either of Java primitive types or their wrappers.
*/
public abstract class Lookup {
/**
* the array size
*/
final protected int s = 50000000;
/**
* Initialize the array: fill in the array with the same
* elements except for the last one.
*/
abstract public void prepare();
/**
* Free the array's reference.
*/
abstract public void clean();
/**
* Find the position of the element that is different from the others.
* By construction, it is the last array element.
*
* @return array's last element index
*/
abstract public int findPosition();
/**
* Get the name of the class that extends this one. It is needed in order
* to set up the benchmark.
*
* @return
*/
abstract public String getSimpleClassName();
Collection<RunResult> run() throws RunnerException {
Options opt = new OptionsBuilder()
.include(getSimpleClassName())
.forks(1)
.build();
return new Runner(opt).run();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/ShortPrimitiveLookup.java
+45
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@@ -0,0 +1,45 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class ShortPrimitiveLookup extends Lookup {
private short[] elements;
private final short pivot = 2;
@Setup
@Override
public void prepare() {
short common = 1;
elements = new short[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@TearDown
@Override
public void clean() {
elements = null;
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
while (pivot != elements[index]) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return ShortPrimitiveLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/primitive/ShortWrapperLookup.java
+46
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@@ -0,0 +1,46 @@
package com.baeldung.primitive;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class ShortWrapperLookup extends Lookup {
private Short[] elements;
private final short pivot = 2;
@Override
@Setup
public void prepare() {
short common = 1;
elements = new Short[s];
for (int i = 0; i < s - 1; i++) {
elements[i] = common;
}
elements[s - 1] = pivot;
}
@Override
@TearDown
public void clean() {
elements = null;
}
@Override
@Benchmark
@BenchmarkMode(Mode.AverageTime)
public int findPosition() {
int index = 0;
Short pivotWrapper = pivot;
while (!pivotWrapper.equals(elements[index])) {
index++;
}
return index;
}
@Override
public String getSimpleClassName() {
return ShortWrapperLookup.class.getSimpleName();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/AddCommand.java
+17
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@@ -0,0 +1,17 @@
package com.baeldung.reducingIfElse;
public class AddCommand implements Command {
private int a;
private int b;
public AddCommand(int a, int b) {
this.a = a;
this.b = b;
}
@Override
public Integer execute() {
return a + b;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/AddRule.java
+21
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@@ -0,0 +1,21 @@
package com.baeldung.reducingIfElse;
public class AddRule implements Rule {
private int result;
@Override
public boolean evaluate(Expression expression) {
boolean evalResult = false;
if (expression.getOperator() == Operator.ADD) {
this.result = expression.getX() + expression.getY();
evalResult = true;
}
return evalResult;
}
@Override
public Result getResult() {
return new Result(result);
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Addition.java
+8
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@@ -0,0 +1,8 @@
package com.baeldung.reducingIfElse;
public class Addition implements Operation {
@Override
public int apply(int a, int b) {
return a + b;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Calculator.java
+83
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package com.baeldung.reducingIfElse;
public class Calculator {
public int calculate(int a, int b, String operator) {
int result = Integer.MIN_VALUE;
if ("add".equals(operator)) {
result = a + b;
} else if ("multiply".equals(operator)) {
result = a * b;
} else if ("divide".equals(operator)) {
result = a / b;
} else if ("subtract".equals(operator)) {
result = a - b;
} else if ("modulo".equals(operator)) {
result = a % b;
}
return result;
}
public int calculateUsingSwitch(int a, int b, String operator) {
int result = 0;
switch (operator) {
case "add":
result = a + b;
break;
case "multiply":
result = a * b;
break;
case "divide":
result = a / b;
break;
case "subtract":
result = a - b;
break;
case "modulo":
result = a % b;
break;
default:
result = Integer.MIN_VALUE;
}
return result;
}
public int calculateUsingSwitch(int a, int b, Operator operator) {
int result = 0;
switch (operator) {
case ADD:
result = a + b;
break;
case MULTIPLY:
result = a * b;
break;
case DIVIDE:
result = a / b;
break;
case SUBTRACT:
result = a - b;
break;
case MODULO:
result = a % b;
break;
default:
result = Integer.MIN_VALUE;
}
return result;
}
public int calculate(int a, int b, Operator operator) {
return operator.apply(a, b);
}
public int calculateUsingFactory(int a, int b, String operation) {
Operation targetOperation = OperatorFactory.getOperation(operation)
.orElseThrow(() -> new IllegalArgumentException("Invalid Operator"));
return targetOperation.apply(a, b);
}
public int calculate(Command command) {
return command.execute();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Command.java
+5
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@@ -0,0 +1,5 @@
package com.baeldung.reducingIfElse;
public interface Command {
Integer execute();
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Division.java
+7
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@@ -0,0 +1,7 @@
package com.baeldung.reducingIfElse;
public class Division implements Operation {
@Override public int apply(int a, int b) {
return a / b;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Expression.java
+26
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@@ -0,0 +1,26 @@
package com.baeldung.reducingIfElse;
public class Expression {
private Integer x;
private Integer y;
private Operator operator;
public Expression(Integer x, Integer y, Operator operator) {
this.x = x;
this.y = y;
this.operator = operator;
}
public Integer getX() {
return x;
}
public Integer getY() {
return y;
}
public Operator getOperator() {
return operator;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Modulo.java
+7
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@@ -0,0 +1,7 @@
package com.baeldung.reducingIfElse;
public class Modulo implements Operation {
@Override public int apply(int a, int b) {
return a % b;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Multiplication.java
+7
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@@ -0,0 +1,7 @@
package com.baeldung.reducingIfElse;
public class Multiplication implements Operation {
@Override public int apply(int a, int b) {
return 0;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Operation.java
+5
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@@ -0,0 +1,5 @@
package com.baeldung.reducingIfElse;
public interface Operation {
int apply(int a, int b);
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Operator.java
+41
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@@ -0,0 +1,41 @@
package com.baeldung.reducingIfElse;
public enum Operator {
ADD {
@Override
public int apply(int a, int b) {
return a + b;
}
},
MULTIPLY {
@Override
public int apply(int a, int b) {
return a * b;
}
},
SUBTRACT {
@Override
public int apply(int a, int b) {
return a - b;
}
},
DIVIDE {
@Override
public int apply(int a, int b) {
return a / b;
}
},
MODULO {
@Override
public int apply(int a, int b) {
return a % b;
}
};
public abstract int apply(int a, int b);
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/OperatorFactory.java
+21
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@@ -0,0 +1,21 @@
package com.baeldung.reducingIfElse;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
public class OperatorFactory {
static Map<String, Operation> operationMap = new HashMap<>();
static {
operationMap.put("add", new Addition());
operationMap.put("divide", new Division());
operationMap.put("multiply", new Multiplication());
operationMap.put("subtract", new Subtraction());
operationMap.put("modulo", new Modulo());
}
public static Optional<Operation> getOperation(String operation) {
return Optional.ofNullable(operationMap.get(operation));
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Result.java
+13
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@@ -0,0 +1,13 @@
package com.baeldung.reducingIfElse;
public class Result {
int value;
public Result(int value) {
this.value = value;
}
public int getValue() {
return value;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Rule.java
+8
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@@ -0,0 +1,8 @@
package com.baeldung.reducingIfElse;
public interface Rule {
boolean evaluate(Expression expression);
Result getResult();
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/RuleEngine.java
+24
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@@ -0,0 +1,24 @@
package com.baeldung.reducingIfElse;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
public class RuleEngine {
private static List<Rule> rules = new ArrayList<>();
static {
rules.add(new AddRule());
}
public Result process(Expression expression) {
Rule rule = rules.stream()
.filter(r -> r.evaluate(expression))
.findFirst()
.orElseThrow(() -> new IllegalArgumentException("Expression does not matches any Rule"));
return rule.getResult();
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/reducingIfElse/Subtraction.java
+7
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@@ -0,0 +1,7 @@
package com.baeldung.reducingIfElse;
public class Subtraction implements Operation {
@Override public int apply(int a, int b) {
return a - b;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/spliteratorAPI/Article.java
+44
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@@ -0,0 +1,44 @@
package com.baeldung.spliteratorAPI;
import java.util.List;
public class Article {
private List<Author> listOfAuthors;
private int id;
private String name;
public Article(String name) {
this.name = name;
}
public Article(List<Author> listOfAuthors, int id) {
super();
this.listOfAuthors = listOfAuthors;
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public List<Author> getListOfAuthors() {
return listOfAuthors;
}
public void setListOfAuthors(List<Author> listOfAuthors) {
this.listOfAuthors = listOfAuthors;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/spliteratorAPI/Author.java
+33
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@@ -0,0 +1,33 @@
package com.baeldung.spliteratorAPI;
public class Author {
private String name;
private int relatedArticleId;
public Author(String name, int relatedArticleId) {
this.name = name;
this.relatedArticleId = relatedArticleId;
}
public int getRelatedArticleId() {
return relatedArticleId;
}
public void setRelatedArticleId(int relatedArticleId) {
this.relatedArticleId = relatedArticleId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "[name: " + name + ", relatedId: " + relatedArticleId + "]";
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/spliteratorAPI/Executor.java
+19
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@@ -0,0 +1,19 @@
package com.baeldung.spliteratorAPI;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class Executor {
public static int countAutors(Stream<Author> stream) {
RelatedAuthorCounter wordCounter = stream.reduce(new RelatedAuthorCounter(0, true),
RelatedAuthorCounter::accumulate, RelatedAuthorCounter::combine);
return wordCounter.getCounter();
}
public static List<Article> generateElements() {
return Stream.generate(() -> new Article("Java")).limit(35000).collect(Collectors.toList());
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/spliteratorAPI/RelatedAuthorCounter.java
+27
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@@ -0,0 +1,27 @@
package com.baeldung.spliteratorAPI;
public class RelatedAuthorCounter {
private final int counter;
private final boolean isRelated;
public RelatedAuthorCounter(int counter, boolean isRelated) {
this.counter = counter;
this.isRelated = isRelated;
}
public RelatedAuthorCounter accumulate(Author author) {
if (author.getRelatedArticleId() == 0) {
return isRelated ? this : new RelatedAuthorCounter(counter, true);
} else {
return isRelated ? new RelatedAuthorCounter(counter + 1, false) : this;
}
}
public RelatedAuthorCounter combine(RelatedAuthorCounter RelatedAuthorCounter) {
return new RelatedAuthorCounter(counter + RelatedAuthorCounter.counter, RelatedAuthorCounter.isRelated);
}
public int getCounter() {
return counter;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/spliteratorAPI/RelatedAuthorSpliterator.java
+49
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@@ -0,0 +1,49 @@
package com.baeldung.spliteratorAPI;
import java.util.List;
import java.util.Spliterator;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Consumer;
public class RelatedAuthorSpliterator implements Spliterator<Author> {
private final List<Author> list;
AtomicInteger current = new AtomicInteger();
public RelatedAuthorSpliterator(List<Author> list) {
this.list = list;
}
@Override
public boolean tryAdvance(Consumer<? super Author> action) {
action.accept(list.get(current.getAndIncrement()));
return current.get() < list.size();
}
@Override
public Spliterator<Author> trySplit() {
int currentSize = list.size() - current.get();
if (currentSize < 10) {
return null;
}
for (int splitPos = currentSize / 2 + current.intValue(); splitPos < list.size(); splitPos++) {
if (list.get(splitPos).getRelatedArticleId() == 0) {
Spliterator<Author> spliterator = new RelatedAuthorSpliterator(list.subList(current.get(), splitPos));
current.set(splitPos);
return spliterator;
}
}
return null;
}
@Override
public long estimateSize() {
return list.size() - current.get();
}
@Override
public int characteristics() {
return CONCURRENT;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/spliteratorAPI/Task.java
+27
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@@ -0,0 +1,27 @@
package com.baeldung.spliteratorAPI;
import java.util.Spliterator;
import java.util.concurrent.Callable;
public class Task implements Callable<String> {
private Spliterator<Article> spliterator;
private final static String SUFFIX = "- published by Baeldung";
public Task(Spliterator<Article> spliterator) {
this.spliterator = spliterator;
}
@Override
public String call() {
int current = 0;
while (spliterator.tryAdvance(article -> {
article.setName(article.getName()
.concat(SUFFIX));
})) {
current++;
}
;
return Thread.currentThread()
.getName() + ":" + current;
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/strategy/ChristmasDiscounter.java
+11
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@@ -0,0 +1,11 @@
package com.baeldung.strategy;
import java.math.BigDecimal;
public class ChristmasDiscounter implements Discounter {
@Override
public BigDecimal apply(BigDecimal amount) {
return amount.multiply(BigDecimal.valueOf(0.9));
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/strategy/Discounter.java
+23
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@@ -0,0 +1,23 @@
package com.baeldung.strategy;
import java.math.BigDecimal;
import java.util.function.UnaryOperator;
public interface Discounter extends UnaryOperator<BigDecimal> {
default Discounter combine(Discounter after) {
return value -> after.apply(this.apply(value));
}
static Discounter christmas() {
return (amount) -> amount.multiply(BigDecimal.valueOf(0.9));
}
static Discounter newYear() {
return (amount) -> amount.multiply(BigDecimal.valueOf(0.8));
}
static Discounter easter() {
return (amount) -> amount.multiply(BigDecimal.valueOf(0.5));
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/strategy/EasterDiscounter.java
+11
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@@ -0,0 +1,11 @@
package com.baeldung.strategy;
import java.math.BigDecimal;
public class EasterDiscounter implements Discounter {
@Override
public BigDecimal apply(BigDecimal amount) {
return amount.multiply(BigDecimal.valueOf(0.5));
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/streamreduce/application/Application.java
+62
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@@ -0,0 +1,62 @@
package com.baeldung.streamreduce.application;
import com.baeldung.streamreduce.entities.User;
import com.baeldung.streamreduce.utilities.NumberUtils;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class Application {
public static void main(String[] args) {
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6);
int result1 = numbers.stream().reduce(0, (a, b) -> a + b);
System.out.println(result1);
int result2 = numbers.stream().reduce(0, Integer::sum);
System.out.println(result2);
List<String> letters = Arrays.asList("a", "b", "c", "d", "e");
String result3 = letters.stream().reduce("", (a, b) -> a + b);
System.out.println(result3);
String result4 = letters.stream().reduce("", String::concat);
System.out.println(result4);
String result5 = letters.stream().reduce("", (a, b) -> a.toUpperCase() + b.toUpperCase());
System.out.println(result5);
List<User> users = Arrays.asList(new User("John", 30), new User("Julie", 35));
int result6 = users.stream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
System.out.println(result6);
String result7 = letters.parallelStream().reduce("", String::concat);
System.out.println(result7);
int result8 = users.parallelStream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
System.out.println(result8);
List<User> userList = new ArrayList<>();
for (int i = 0; i <= 1000000; i++) {
userList.add(new User("John" + i, i));
}
long t1 = System.currentTimeMillis();
int result9 = userList.stream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
long t2 = System.currentTimeMillis();
System.out.println(result9);
System.out.println("Sequential stream time: " + (t2 - t1) + "ms");
long t3 = System.currentTimeMillis();
int result10 = userList.parallelStream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
long t4 = System.currentTimeMillis();
System.out.println(result10);
System.out.println("Parallel stream time: " + (t4 - t3) + "ms");
int result11 = NumberUtils.divideListElements(numbers, 1);
System.out.println(result11);
int result12 = NumberUtils.divideListElementsWithExtractedTryCatchBlock(numbers, 0);
System.out.println(result12);
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/streamreduce/entities/User.java
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package com.baeldung.streamreduce.entities;
public class User {
private final String name;
private final int age;
public User(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
@Override
public String toString() {
return "User{" + "name=" + name + ", age=" + age + '}';
}
}
core-java-modules/core-java-8/src/main/java/com/baeldung/streamreduce/utilities/NumberUtils.java
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package com.baeldung.streamreduce.utilities;
import java.util.List;
import java.util.function.BiFunction;
import java.util.logging.Level;
import java.util.logging.Logger;
public abstract class NumberUtils {
private static final Logger LOGGER = Logger.getLogger(NumberUtils.class.getName());
public static int divideListElements(List<Integer> values, Integer divider) {
return values.stream()
.reduce(0, (a, b) -> {
try {
return a / divider + b / divider;
} catch (ArithmeticException e) {
LOGGER.log(Level.INFO, "Arithmetic Exception: Division by Zero");
}
return 0;
});
}
public static int divideListElementsWithExtractedTryCatchBlock(List<Integer> values, int divider) {
return values.stream().reduce(0, (a, b) -> divide(a, divider) + divide(b, divider));
}
public static int divideListElementsWithApplyFunctionMethod(List<Integer> values, int divider) {
BiFunction<Integer, Integer, Integer> division = (a, b) -> a / b;
return values.stream().reduce(0, (a, b) -> applyFunction(division, a, divider) + applyFunction(division, b, divider));
}
private static int divide(int value, int factor) {
int result = 0;
try {
result = value / factor;
} catch (ArithmeticException e) {
LOGGER.log(Level.INFO, "Arithmetic Exception: Division by Zero");
}
return result;
}
private static int applyFunction(BiFunction<Integer, Integer, Integer> function, int a, int b) {
try {
return function.apply(a, b);
}
catch(Exception e) {
LOGGER.log(Level.INFO, "Exception occurred!");
}
return 0;
}
}
core-java-modules/core-java-8/src/main/resources/logback.xml
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<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
</pattern>
</encoder>
</appender>
<root level="INFO">
<appender-ref ref="STDOUT" />
</root>
</configuration>
core-java-modules/core-java-8/src/test/java/com/baeldung/collectors/Java8CollectorsUnitTest.java
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package com.baeldung.collectors;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import org.junit.Test;
import java.util.Arrays;
import java.util.Comparator;
import java.util.DoubleSummaryStatistics;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;
import static com.google.common.collect.Sets.newHashSet;
import static java.util.stream.Collectors.averagingDouble;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.maxBy;
import static java.util.stream.Collectors.partitioningBy;
import static java.util.stream.Collectors.summarizingDouble;
import static java.util.stream.Collectors.summingDouble;
import static java.util.stream.Collectors.toCollection;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toMap;
import static java.util.stream.Collectors.toSet;
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatThrownBy;
public class Java8CollectorsUnitTest {
private final List<String> givenList = Arrays.asList("a", "bb", "ccc", "dd");
private final List<String> listWithDuplicates = Arrays.asList("a", "bb", "c", "d", "bb");
@Test
public void whenCollectingToList_shouldCollectToList() throws Exception {
final List<String> result = givenList.stream().collect(toList());
assertThat(result).containsAll(givenList);
}
@Test
public void whenCollectingToSet_shouldCollectToSet() throws Exception {
final Set<String> result = givenList.stream().collect(toSet());
assertThat(result).containsAll(givenList);
}
@Test
public void givenContainsDuplicateElements_whenCollectingToSet_shouldAddDuplicateElementsOnlyOnce() throws Exception {
final Set<String> result = listWithDuplicates.stream().collect(toSet());
assertThat(result).hasSize(4);
}
@Test
public void whenCollectingToCollection_shouldCollectToCollection() throws Exception {
final List<String> result = givenList.stream().collect(toCollection(LinkedList::new));
assertThat(result).containsAll(givenList).isInstanceOf(LinkedList.class);
}
@Test
public void whenCollectingToImmutableCollection_shouldThrowException() throws Exception {
assertThatThrownBy(() -> {
givenList.stream().collect(toCollection(ImmutableList::of));
}).isInstanceOf(UnsupportedOperationException.class);
}
@Test
public void whenCollectingToMap_shouldCollectToMap() throws Exception {
final Map<String, Integer> result = givenList.stream().collect(toMap(Function.identity(), String::length));
assertThat(result).containsEntry("a", 1).containsEntry("bb", 2).containsEntry("ccc", 3).containsEntry("dd", 2);
}
@Test
public void whenCollectingToMapwWithDuplicates_shouldCollectToMapMergingTheIdenticalItems() throws Exception {
final Map<String, Integer> result = listWithDuplicates.stream().collect(
toMap(
Function.identity(),
String::length,
(item, identicalItem) -> item
)
);
assertThat(result).containsEntry("a", 1).containsEntry("bb", 2).containsEntry("c", 1).containsEntry("d", 1);
}
@Test
public void givenContainsDuplicateElements_whenCollectingToMap_shouldThrowException() throws Exception {
assertThatThrownBy(() -> {
listWithDuplicates.stream().collect(toMap(Function.identity(), String::length));
}).isInstanceOf(IllegalStateException.class);
}
@Test
public void whenCollectingAndThen_shouldCollect() throws Exception {
final List<String> result = givenList.stream().collect(collectingAndThen(toList(), ImmutableList::copyOf));
assertThat(result).containsAll(givenList).isInstanceOf(ImmutableList.class);
}
@Test
public void whenJoining_shouldJoin() throws Exception {
final String result = givenList.stream().collect(joining());
assertThat(result).isEqualTo("abbcccdd");
}
@Test
public void whenJoiningWithSeparator_shouldJoinWithSeparator() throws Exception {
final String result = givenList.stream().collect(joining(" "));
assertThat(result).isEqualTo("a bb ccc dd");
}
@Test
public void whenJoiningWithSeparatorAndPrefixAndPostfix_shouldJoinWithSeparatorPrePost() throws Exception {
final String result = givenList.stream().collect(joining(" ", "PRE-", "-POST"));
assertThat(result).isEqualTo("PRE-a bb ccc dd-POST");
}
@Test
public void whenPartitioningBy_shouldPartition() throws Exception {
final Map<Boolean, List<String>> result = givenList.stream().collect(partitioningBy(s -> s.length() > 2));
assertThat(result).containsKeys(true, false).satisfies(booleanListMap -> {
assertThat(booleanListMap.get(true)).contains("ccc");
assertThat(booleanListMap.get(false)).contains("a", "bb", "dd");
});
}
@Test
public void whenCounting_shouldCount() throws Exception {
final Long result = givenList.stream().collect(counting());
assertThat(result).isEqualTo(4);
}
@Test
public void whenSummarizing_shouldSummarize() throws Exception {
final DoubleSummaryStatistics result = givenList.stream().collect(summarizingDouble(String::length));
assertThat(result.getAverage()).isEqualTo(2);
assertThat(result.getCount()).isEqualTo(4);
assertThat(result.getMax()).isEqualTo(3);
assertThat(result.getMin()).isEqualTo(1);
assertThat(result.getSum()).isEqualTo(8);
}
@Test
public void whenAveraging_shouldAverage() throws Exception {
final Double result = givenList.stream().collect(averagingDouble(String::length));
assertThat(result).isEqualTo(2);
}
@Test
public void whenSumming_shouldSum() throws Exception {
final Double result = givenList.stream().filter(i -> true).collect(summingDouble(String::length));
assertThat(result).isEqualTo(8);
}
@Test
public void whenMaxingBy_shouldMaxBy() throws Exception {
final Optional<String> result = givenList.stream().collect(maxBy(Comparator.naturalOrder()));
assertThat(result).isPresent().hasValue("dd");
}
@Test
public void whenGroupingBy_shouldGroupBy() throws Exception {
final Map<Integer, Set<String>> result = givenList.stream().collect(groupingBy(String::length, toSet()));
assertThat(result).containsEntry(1, newHashSet("a")).containsEntry(2, newHashSet("bb", "dd")).containsEntry(3, newHashSet("ccc"));
}
@Test
public void whenCreatingCustomCollector_shouldCollect() throws Exception {
final ImmutableSet<String> result = givenList.stream().collect(toImmutableSet());
assertThat(result).isInstanceOf(ImmutableSet.class).contains("a", "bb", "ccc", "dd");
}
private static <T> ImmutableSetCollector<T> toImmutableSet() {
return new ImmutableSetCollector<>();
}
private static class ImmutableSetCollector<T> implements Collector<T, ImmutableSet.Builder<T>, ImmutableSet<T>> {
@Override
public Supplier<ImmutableSet.Builder<T>> supplier() {
return ImmutableSet::builder;
}
@Override
public BiConsumer<ImmutableSet.Builder<T>, T> accumulator() {
return ImmutableSet.Builder::add;
}
@Override
public BinaryOperator<ImmutableSet.Builder<T>> combiner() {
return (left, right) -> left.addAll(right.build());
}
@Override
public Function<ImmutableSet.Builder<T>, ImmutableSet<T>> finisher() {
return ImmutableSet.Builder::build;
}
@Override
public Set<Characteristics> characteristics() {
return Sets.immutableEnumSet(Characteristics.UNORDERED);
}
}
}
core-java-modules/core-java-8/src/test/java/com/baeldung/counter/CounterStatistics.java
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package com.baeldung.counter;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Mode;
import com.baeldung.counter.CounterUtil.MutableInteger;
@Fork(value = 1, warmups = 3)
@BenchmarkMode(Mode.All)
public class CounterStatistics {
private static final Map<String, Integer> counterMap = new HashMap<>();
private static final Map<String, MutableInteger> counterWithMutableIntMap = new HashMap<>();
private static final Map<String, int[]> counterWithIntArrayMap = new HashMap<>();
private static final Map<String, Long> counterWithLongWrapperMap = new HashMap<>();
private static final Map<String, Long> counterWithLongWrapperStreamMap = new HashMap<>();
static {
CounterUtil.COUNTRY_NAMES = new String[10000];
final String prefix = "NewString";
Random random = new Random();
for (int i=0; i<10000; i++) {
CounterUtil.COUNTRY_NAMES[i] = new String(prefix + random.nextInt(1000));
}
}
@Benchmark
public void wrapperAsCounter() {
CounterUtil.counterWithWrapperObject(counterMap);
}
@Benchmark
public void lambdaExpressionWithWrapper() {
CounterUtil.counterWithLambdaAndWrapper(counterWithLongWrapperMap);
}
@Benchmark
public void parallelStreamWithWrapper() {
CounterUtil.counterWithParallelStreamAndWrapper(counterWithLongWrapperStreamMap);
}
@Benchmark
public void mutableIntegerAsCounter() {
CounterUtil.counterWithMutableInteger(counterWithMutableIntMap);
}
@Benchmark
public void primitiveArrayAsCounter() {
CounterUtil.counterWithPrimitiveArray(counterWithIntArrayMap);
}
public static void main(String[] args) throws Exception {
org.openjdk.jmh.Main.main(args);
}
}

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