Merge pull request #548 from eugenp/grzegorz-immutables

Add examples for "Introduction to Immutables" article

immutables/pom.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>immutables</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.immutables</groupId>
+            <artifactId>value</artifactId>
+            <version>2.2.10</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.5.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mutabilitydetector</groupId>
+            <artifactId>MutabilityDetector</artifactId>
+            <version>0.9.5</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.3</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

immutables/src/main/java/com/baeldung/immutable/Address.java

@@ -0,0 +1,9 @@
+package com.baeldung.immutable;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+public interface Address {
+    String getStreetName();
+    Integer getNumber();
+}

immutables/src/main/java/com/baeldung/immutable/Person.java

@@ -0,0 +1,9 @@
+package com.baeldung.immutable;
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+public abstract class Person {
+    abstract String getName();
+    abstract Integer getAge();
+}

immutables/src/main/java/com/baeldung/immutable/auxiliary/Person.java

@@ -0,0 +1,13 @@
+package com.baeldung.immutable.auxiliary;
+
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+public abstract class Person {
+    abstract String getName();
+    abstract Integer getAge();
+
+    @Value.Auxiliary
+    abstract String getAuxiliaryField();
+}

immutables/src/main/java/com/baeldung/immutable/default_/Person.java

@@ -0,0 +1,14 @@
+package com.baeldung.immutable.default_;
+
+import org.immutables.value.Value;
+
+@Value.Immutable(prehash = true)
+public abstract class Person {
+
+    abstract String getName();
+
+    @Value.Default
+    Integer getAge() {
+        return 42;
+    }
+}

immutables/src/main/java/com/baeldung/immutable/parameter/Person.java

@@ -0,0 +1,14 @@
+package com.baeldung.immutable.parameter;
+
+
+import org.immutables.value.Value;
+
+@Value.Immutable
+public abstract class Person {
+
+    @Value.Parameter
+    abstract String getName();
+
+    @Value.Parameter
+    abstract Integer getAge();
+}

immutables/src/main/java/com/baeldung/immutable/prehash/Person.java

@@ -0,0 +1,9 @@
+package com.baeldung.immutable.prehash;
+
+import org.immutables.value.Value;
+
+@Value.Immutable(prehash = true)
+public abstract class Person {
+    abstract String getName();
+    abstract Integer getAge();
+}

immutables/src/test/java/com/baeldung/immutable/ImmutablePersonTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.immutable;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mutabilitydetector.unittesting.MutabilityAssert.assertImmutable;
+
+public class ImmutablePersonTest {
+
+    @Test
+    public void whenModifying_shouldCreateNewInstance() throws Exception {
+        final ImmutablePerson john = ImmutablePerson.builder()
+          .age(42)
+          .name("John")
+          .build();
+
+        final ImmutablePerson john43 = john.withAge(43);
+
+        assertThat(john)
+          .isNotSameAs(john43);
+
+        assertThat(john.getAge())
+          .isEqualTo(42);
+
+        assertImmutable(ImmutablePerson.class);
+    }
+}

immutables/src/test/java/com/baeldung/immutable/auxiliary/ImmutablePersonAuxiliaryTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.immutable.auxiliary;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ImmutablePersonAuxiliaryTest {
+
+    @Test
+    public void whenComparing_shouldIgnore() throws Exception {
+        final ImmutablePerson john1 = ImmutablePerson.builder()
+          .name("John")
+          .age(42)
+          .auxiliaryField("Value1")
+          .build();
+
+        final ImmutablePerson john2 = ImmutablePerson.builder()
+          .name("John")
+          .age(42)
+          .auxiliaryField("Value2")
+          .build();
+
+
+        assertThat(john1.equals(john2))
+          .isTrue();
+
+        assertThat(john1.toString())
+          .isEqualTo(john2.toString());
+
+        assertThat(john1.hashCode())
+          .isEqualTo(john2.hashCode());
+    }
+}

immutables/src/test/java/com/baeldung/immutable/default_/ImmutablePersonDefaultTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.immutable.default_;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ImmutablePersonDefaultTest {
+
+    @Test
+    public void whenInstantiating_shouldUseDefaultValue() throws Exception {
+
+        final ImmutablePerson john = ImmutablePerson.builder().name("John").build();
+
+        assertThat(john.getAge()).isEqualTo(42);
+
+    }
+}

pom.xml

@@ -31,6 +31,7 @@
         <module>guava19</module>
         <module>handling-spring-static-resources</module>
         <module>httpclient</module>
+        <module>immutables</module>
         <module>jackson</module>
         <module>javaxval</module>
         <module>jjwt</module>