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[JAVA-22519] Created new module libraries-stream and added 5 articles (#15403)

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This commit is contained in:
panos-kakos
2023-12-13 09:40:13 +02:00
committed by GitHub
parent 0323a8168c
commit 8daf19c9ec
92 changed files with 718 additions and 430 deletions
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libraries-5/README.md
-2
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@@ -9,10 +9,8 @@ Remember, for advanced libraries like [Jackson](/jackson) and [JUnit](/testing-m
### Relevant articles
- [Introduction to Caffeine](https://www.baeldung.com/java-caching-caffeine)
- [Introduction to StreamEx](https://www.baeldung.com/streamex)
- [A Docker Guide for Java](https://www.baeldung.com/docker-java-api)
- [Introduction to Akka Actors in Java](https://www.baeldung.com/akka-actors-java)
- [A Guide to Byte Buddy](https://www.baeldung.com/byte-buddy)
- [Introduction to jOOL](https://www.baeldung.com/jool)
- [Consumer Driven Contracts with Pact](https://www.baeldung.com/pact-junit-consumer-driven-contracts)
- [Introduction to Atlassian Fugue](https://www.baeldung.com/java-fugue)
libraries-5/pom.xml
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@@ -49,21 +49,6 @@
<version>${typesafe-akka.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>one.util</groupId>
<artifactId>streamex</artifactId>
<version>${streamex.version}</version>
</dependency>
<dependency>
<groupId>net.bytebuddy</groupId>
<artifactId>byte-buddy</artifactId>
<version>${byte-buddy.version}</version>
</dependency>
<dependency>
<groupId>net.bytebuddy</groupId>
<artifactId>byte-buddy-agent</artifactId>
<version>${byte-buddy.version}</version>
</dependency>
<!--Java Docker API Client -->
<dependency>
<groupId>com.github.docker-java</groupId>
@@ -139,7 +124,6 @@
<spring.version>4.3.8.RELEASE</spring.version>
<scala.version>2.12</scala.version>
<typesafe-akka.version>2.5.11</typesafe-akka.version>
<streamex.version>0.8.1</streamex.version>
<docker.version>3.0.14</docker.version>
<caffeine.version>3.1.8</caffeine.version>
<findbugs.version>3.0.2</findbugs.version>
libraries-5/src/main/java/com/baeldung/bytebuddy/Bar.java
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@@ -1,21 +0,0 @@
package com.baeldung.bytebuddy;
import net.bytebuddy.implementation.bind.annotation.BindingPriority;
public class Bar {
@BindingPriority(3)
public static String sayHelloBar() {
return "Holla in Bar!";
}
@BindingPriority(2)
public static String sayBar() {
return "bar";
}
public String bar() {
return Bar.class.getSimpleName() + " - Bar";
}
}
libraries-5/src/main/java/com/baeldung/bytebuddy/Foo.java
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@@ -1,9 +0,0 @@
package com.baeldung.bytebuddy;
public class Foo {
public String sayHelloFoo() {
return "Hello in Foo!";
}
}
libraries-5/src/main/java/com/baeldung/streamex/Role.java
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@@ -1,5 +0,0 @@
package com.baeldung.streamex;
public class Role {
}
libraries-5/src/main/java/com/baeldung/streamex/StreamEX.java
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@@ -1,58 +0,0 @@
package com.baeldung.streamex;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;
import one.util.streamex.DoubleStreamEx;
import one.util.streamex.EntryStream;
import one.util.streamex.IntStreamEx;
import one.util.streamex.StreamEx;
public class StreamEX {
public static void main(String[] args) {
// Collector shortcut methods (toList, toSet, groupingBy, joining, etc.)
List<User> users = Arrays.asList(new User("name"), new User(), new User());
users.stream().map(User::getName).collect(Collectors.toList());
List<String> userNames = StreamEx.of(users).map(User::getName).toList();
Map<Role, List<User>> role2users = StreamEx.of(users).groupingBy(User::getRole);
StreamEx.of(1, 2, 3).joining("; "); // "1; 2; 3"
// Selecting stream elements of specific type
List usersAndRoles = Arrays.asList(new User(), new Role());
List<Role> roles = IntStreamEx.range(usersAndRoles.size()).mapToObj(usersAndRoles::get).select(Role.class).toList();
System.out.println(roles);
// adding elements to Stream
List<String> appendedUsers = StreamEx.of(users).map(User::getName).prepend("(none)").append("LAST").toList();
System.out.println(appendedUsers);
// Removing unwanted elements and using the stream as Iterable:
for (String line : StreamEx.of(users).map(User::getName).nonNull()) {
System.out.println(line);
}
// Selecting map keys by value predicate:
Map<String, Role> nameToRole = new HashMap<>();
nameToRole.put("first", new Role());
nameToRole.put("second", null);
Set<String> nonNullRoles = StreamEx.ofKeys(nameToRole, Objects::nonNull).toSet();
System.out.println(nonNullRoles);
// Operating on key-value pairs:
Map<User, List<Role>> users2roles = transformMap(role2users);
Map<String, String> mapToString = EntryStream.of(users2roles).mapKeys(String::valueOf).mapValues(String::valueOf).toMap();
// Support of byte/char/short/float types:
short[] src = { 1, 2, 3 };
char[] output = IntStreamEx.of(src).map(x -> x * 5).toCharArray();
}
public double[] getDiffBetweenPairs(double... numbers) {
return DoubleStreamEx.of(numbers).pairMap((a, b) -> b - a).toArray();
}
public static Map<User, List<Role>> transformMap(Map<Role, List<User>> role2users) {
Map<User, List<Role>> users2roles = EntryStream.of(role2users).flatMapValues(List::stream).invert().grouping();
return users2roles;
}
}
libraries-5/src/main/java/com/baeldung/streamex/User.java
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@@ -1,40 +0,0 @@
package com.baeldung.streamex;
public class User {
int id;
String name;
Role role = new Role();
public User() {
}
public User(String name) {
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Role getRole() {
return role;
}
public void setRole(Role role) {
this.role = role;
}
}
libraries-5/src/test/java/com/baeldung/bytebuddy/ByteBuddyUnitTest.java
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@@ -1,60 +0,0 @@
package com.baeldung.bytebuddy;
import net.bytebuddy.ByteBuddy;
import net.bytebuddy.agent.ByteBuddyAgent;
import net.bytebuddy.dynamic.DynamicType;
import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
import net.bytebuddy.dynamic.loading.ClassReloadingStrategy;
import net.bytebuddy.implementation.FixedValue;
import net.bytebuddy.implementation.MethodDelegation;
import net.bytebuddy.matcher.ElementMatchers;
import org.junit.Test;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import static net.bytebuddy.matcher.ElementMatchers.*;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
public class ByteBuddyUnitTest {
@Test
public void givenObject_whenToString_thenReturnHelloWorldString() throws InstantiationException, IllegalAccessException {
DynamicType.Unloaded unloadedType = new ByteBuddy().subclass(Object.class).method(ElementMatchers.isToString()).intercept(FixedValue.value("Hello World ByteBuddy!")).make();
Class<?> dynamicType = unloadedType.load(getClass().getClassLoader()).getLoaded();
assertEquals(dynamicType.newInstance().toString(), "Hello World ByteBuddy!");
}
@Test
public void givenFoo_whenRedefined_thenReturnFooRedefined() throws Exception {
ByteBuddyAgent.install();
new ByteBuddy().redefine(Foo.class).method(named("sayHelloFoo")).intercept(FixedValue.value("Hello Foo Redefined")).make().load(Foo.class.getClassLoader(), ClassReloadingStrategy.fromInstalledAgent());
Foo f = new Foo();
assertEquals(f.sayHelloFoo(), "Hello Foo Redefined");
}
@Test
public void givenSayHelloFoo_whenMethodDelegation_thenSayHelloBar() throws IllegalAccessException, InstantiationException {
String r = new ByteBuddy().subclass(Foo.class).method(named("sayHelloFoo").and(isDeclaredBy(Foo.class).and(returns(String.class)))).intercept(MethodDelegation.to(Bar.class)).make().load(getClass().getClassLoader()).getLoaded().newInstance()
.sayHelloFoo();
assertEquals(r, Bar.sayHelloBar());
}
@Test
public void givenMethodName_whenDefineMethod_thenCreateMethod() throws Exception {
Class<?> type = new ByteBuddy().subclass(Object.class).name("MyClassName").defineMethod("custom", String.class, Modifier.PUBLIC).intercept(MethodDelegation.to(Bar.class)).defineField("x", String.class, Modifier.PUBLIC).make()
.load(getClass().getClassLoader(), ClassLoadingStrategy.Default.WRAPPER).getLoaded();
Method m = type.getDeclaredMethod("custom", null);
assertEquals(m.invoke(type.newInstance()), Bar.sayHelloBar());
assertNotNull(type.getDeclaredField("x"));
}
}
libraries-5/src/test/java/com/baeldung/streamex/StreamExMergeStreamsUnitTest.java
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@@ -1,47 +0,0 @@
package com.baeldung.streamex;
import one.util.streamex.StreamEx;
import org.junit.Test;
import java.util.Arrays;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static org.junit.Assert.assertEquals;
public class StreamExMergeStreamsUnitTest {
@Test
public void givenTwoStreams_whenMergingStreams_thenResultingStreamContainsElementsFromBothStreams() {
Stream<Integer> stream1 = Stream.of(1, 3, 5);
Stream<Integer> stream2 = Stream.of(2, 4, 6);
Stream<Integer> resultingStream = StreamEx.of(stream1).append(stream2);
assertEquals(Arrays.asList(1, 3, 5, 2, 4, 6), resultingStream.collect(Collectors.toList()));
}
@Test
public void givenFourStreams_whenMergingStreams_thenResultingStreamContainsElementsFromAllStreams() {
Stream<Integer> stream1 = Stream.of(1, 3, 5);
Stream<Integer> stream2 = Stream.of(2, 4, 6);
Stream<Integer> stream3 = Stream.of(18, 15, 36);
Stream<Integer> stream4 = Stream.of(99);
Stream<Integer> resultingStream = StreamEx.of(stream1).append(stream2).append(stream3).append(stream4);
assertEquals(Arrays.asList(1, 3, 5, 2, 4, 6, 18, 15, 36, 99), resultingStream.collect(Collectors.toList()));
}
@Test
public void givenThreeStreams_whenAppendingAndPrependingStreams_thenResultingStreamContainsElementsFromAllStreams() {
Stream<String> stream1 = Stream.of("foo", "bar");
Stream<String> openingBracketStream = Stream.of("[");
Stream<String> closingBracketStream = Stream.of("]");
Stream<String> resultingStream = StreamEx.of(stream1).append(closingBracketStream).prepend(openingBracketStream);
assertEquals(Arrays.asList("[", "foo", "bar", "]"), resultingStream.collect(Collectors.toList()));
}
}