[BAEL-9555] - Created a core-java-modules folder

2019-05-05 17:22:09 +05:30
parent 8b63b0d90a
commit 3bae5e5334
1480 changed files with 25600 additions and 5594 deletions
@@ -0,0 +1,5 @@
+package com.baeldung.annotations;
+
+@Deprecated
+class ClassWithAnnotation {
+}
@@ -0,0 +1,9 @@
+package com.baeldung.annotations;
+
+class ClassWithDeprecatedMethod {
+
+    @Deprecated
+    static void deprecatedMethod() {
+
+    }
+}
@@ -0,0 +1,11 @@
+package com.baeldung.annotations;
+
+class ClassWithSafeVarargs<T> {
+
+    @SafeVarargs
+    final void iterateOverVarargs(T... args) {
+        for (T x : args) {
+            // do stuff with x
+        }
+    }
+}
@@ -0,0 +1,9 @@
+package com.baeldung.annotations;
+
+class ClassWithSuppressWarnings {
+
+    @SuppressWarnings("deprecation")
+    void useDeprecatedMethod() {
+        ClassWithDeprecatedMethod.deprecatedMethod(); // no warning is generated here
+    }
+}
@@ -0,0 +1,8 @@
+package com.baeldung.annotations;
+
+@FunctionalInterface
+interface IntConsumer {
+
+    void accept(Integer number);
+
+}
@@ -0,0 +1,8 @@
+package com.baeldung.annotations;
+
+import java.lang.annotation.Repeatable;
+
+@Repeatable(Intervals.class)
+@interface Interval {
+    int hour() default 1;
+}
@@ -0,0 +1,9 @@
+package com.baeldung.annotations;
+
+public class IntervalUsage {
+
+    @Interval(hour = 17)
+    @Interval(hour = 13)
+    void doPeriodicCleanup() {
+    }
+}
@@ -0,0 +1,5 @@
+package com.baeldung.annotations;
+
+@interface Intervals {
+    Interval[] value();
+}
@@ -0,0 +1,11 @@
+package com.baeldung.annotations;
+
+import java.lang.annotation.*;
+
+@Inherited
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.LOCAL_VARIABLE, ElementType.FIELD})
+@interface MyAnnotation {
+
+}
@@ -0,0 +1,16 @@
+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;
+    }
+}
@@ -0,0 +1,6 @@
+package com.baeldung.annotations;
+
+interface MyOperation {
+
+    void perform();
+}
@@ -0,0 +1,9 @@
+package com.baeldung.annotations;
+
+class MyOperationImpl implements MyOperation {
+
+    @Override
+    public void perform() {
+
+    }
+}
@@ -0,0 +1,9 @@
+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;
+    }
+}
@@ -0,0 +1,13 @@
+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 {
+
+}
@@ -0,0 +1,13 @@
+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 "";
+}
@@ -0,0 +1,13 @@
+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 {
+
+}
@@ -0,0 +1,10 @@
+package com.baeldung.customannotations;
+
+public class JsonSerializationException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public JsonSerializationException(String message) {
+        super(message);
+    }
+}
@@ -0,0 +1,67 @@
+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;
+    }
+}
@@ -0,0 +1,66 @@
+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;
+    }
+
+}
@@ -0,0 +1,18 @@
+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));
+    }
+}
@@ -0,0 +1,12 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public interface Alarm {
+
+    default String turnAlarmOn() {
+        return "Turning the alarm on.";
+    }
+
+    default String turnAlarmOff() {
+        return "Turning the alarm off.";
+    }
+}
@@ -0,0 +1,25 @@
+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.";
+    }
+}
@@ -0,0 +1,25 @@
+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.";
+    }
+}
@@ -0,0 +1,35 @@
+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();
+    }
+}
@@ -0,0 +1,22 @@
+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;
+    }
+}
@@ -0,0 +1,85 @@
+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;
+    }
+}
@@ -0,0 +1,27 @@
+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);
+        }
+    }
+
+}
@@ -0,0 +1,39 @@
+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);
+
+    }
+}
@@ -0,0 +1,10 @@
+package com.baeldung.doublecolon.function;
+
+import com.baeldung.doublecolon.Computer;
+
+@FunctionalInterface
+public interface ComputerPredicate {
+
+    boolean filter(Computer c);
+
+}
@@ -0,0 +1,15 @@
+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));
+    }
+}
--- a/Show More
+++ b/Show More