[BAEL-4281] Examples of array comparisons

java-collections/README.md

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+## Java Collections Examples
+
+This module support code for articles about handling java collections and arrays.
+
+### Relevant Articles: 
+- [Comparing two integer arrays in Java](https://stackoverflow.com/questions/14897366/comparing-two-integer-arrays-in-java)
+- [Compare two arrays with not the same order](https://stackoverflow.com/questions/54711228/compare-two-arrays-with-not-the-same-order)
+- More articles: [[next -->]](../java-collections-conversions-2)

java-collections/pom.xml

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+<?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>
+    <artifactId>java-collections</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>java-collections</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>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-all</artifactId>
+            <version>${hamcrest-all.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>java-collections</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <commons-collections4.version>4.1</commons-collections4.version>
+    </properties>
+</project>

java-collections/src/main/java/com/baeldung/comparingarrays/Plane.java

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+package com.baeldung.comparingarrays;
+
+import java.util.Objects;
+
+public class Plane {
+
+    private final String name;
+
+    private final String model;
+
+    public Plane(String name, String model) {
+
+        this.name = name;
+        this.model = model;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Plane plane = (Plane) o;
+        return Objects.equals(name, plane.name) && Objects.equals(model, plane.model);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, model);
+    }
+}

java-collections/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>

java-collections/src/test/java/com/baeldung/DeepEqualsCompareUnitTest.java

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+package com.baeldung;
+
+import com.baeldung.comparingarrays.Plane;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class DeepEqualsCompareUnitTest {
+
+    @Test
+    public void givenArray1andArray2_whenSameContent_thenDeepEquals() {
+        final Plane[][] planes1 = new Plane[][] { new Plane[] { new Plane("Plane 1", "A320") },
+            new Plane[] { new Plane("Plane 2", "B738") } };
+        final Plane[][] planes2 = new Plane[][] { new Plane[] { new Plane("Plane 1", "A320") },
+            new Plane[] { new Plane("Plane 2", "B738") } };
+
+        boolean result = Arrays.deepEquals(planes1, planes2);
+        assertTrue("Result is not true", result);
+    }
+
+    @Test
+    public void givenArray1andArray2_whenNotSameContent_thenNotDeepEquals() {
+        final Plane[][] planes1 = new Plane[][] { new Plane[] { new Plane("Plane 1", "A320") },
+            new Plane[] { new Plane("Plane 2", "B738") } };
+        final Plane[][] planes2 = new Plane[][] { new Plane[] { new Plane("Plane 2", "B738") },
+            new Plane[] { new Plane("Plane 1", "A320") } };
+
+        boolean result = Arrays.deepEquals(planes1, planes2);
+        assertFalse("Result is true", result);
+    }
+}

java-collections/src/test/java/com/baeldung/EqualsCompareUnitTest.java

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+package com.baeldung;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class EqualsCompareUnitTest {
+
+    @Test
+    public void givenArray1andArray2_whenSameContent_thenEquals() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+
+        boolean result = Arrays.equals(planes1, planes2);
+        assertTrue("Result is not true", result);
+    }
+
+    @Test
+    public void givenArray1andArray2_whenSameContentOtherSort_thenNotEquals() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = new String[] { "B738", "A320", "A321", "A319", "B77W", "B737", "A333", "A332" };
+
+        boolean result = Arrays.equals(planes1, planes2);
+        assertFalse("Result is true", result);
+    }
+}

java-collections/src/test/java/com/baeldung/LengthsCompareUnitTest.java

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+package com.baeldung;
+
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.collection.IsArrayWithSize.arrayWithSize;
+import static org.junit.Assert.assertThat;
+
+public class LengthsCompareUnitTest {
+
+    @Test
+    public void givenArray1andArray2_whenSameSizes_thenSizeEqualsOk() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final Integer[] quantities = new Integer[] { 10, 12, 34, 45, 12, 43, 5, 2 };
+
+        assertThat(planes1, arrayWithSize(8));
+        assertThat(quantities, arrayWithSize(8));
+        assertThat(planes1.length, is(8));
+        assertThat(quantities.length, is(8));
+    }
+}
+

java-collections/src/test/java/com/baeldung/OrderCompareUnitTest.java

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+package com.baeldung;
+
+import com.baeldung.comparingarrays.Plane;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+import static org.junit.Assert.assertTrue;
+
+public class OrderCompareUnitTest {
+    @Test
+    public void givenArray1andArray2_whenNotSameContent_thenNotDeepEquals() {
+        final Plane[][] planes1 = new Plane[][] {
+            new Plane[] { new Plane("Plane 1", "A320"), new Plane("Plane 2", "B738") } };
+        final Plane[][] planes2 = new Plane[][] {
+            new Plane[] { new Plane("Plane 2", "B738"), new Plane("Plane 1", "A320") } };
+
+        Comparator<Plane> planeComparator = (o1, o2) -> {
+            if (o1.getName()
+                .equals(o2.getName())) {
+                return o2.getModel()
+                    .compareTo(o1.getModel());
+            }
+            return o2.getName()
+                .compareTo(o1.getName());
+        };
+        Arrays.sort(planes1[0], planeComparator);
+        Arrays.sort(planes2[0], planeComparator);
+
+        boolean result = Arrays.deepEquals(planes1, planes2);
+        assertTrue("Result is false", result);
+    }
+}

java-collections/src/test/java/com/baeldung/ReferenceCompareUnitTest.java

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+package com.baeldung;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertSame;
+
+public class ReferenceCompareUnitTest {
+
+    @Test
+    public void givenArray1andArray2_whenEquals_thenEqual() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = planes1;
+
+        assertSame("Objects are not equal!", planes1, planes2);
+
+        planes2[0] = "747";
+
+        assertSame("Objects are not same!", planes1, planes2);
+        assertEquals("Objects are not equal!", "747", planes2[0]);
+        assertEquals("Objects are not equal!", "747", planes1[0]);
+    }
+
+    @Test
+    public void givenArray1andArray2_whenDifferentValues_thenNotEqual() {
+        final String[] planes1 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+        final String[] planes2 = new String[] { "A320", "B738", "A321", "A319", "B77W", "B737", "A333", "A332" };
+
+        assertNotSame("Objects are the same!", planes1, planes2);
+        assertNotEquals("Objects are equal!", planes1, planes2);
+    }
+}