Merge branch 'master' into BAEL-16646-2

core-java-modules/core-java-lang-operators/README.md

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+## Relevant Articles:
+- [Guide to the Diamond Operator in Java](https://www.baeldung.com/java-diamond-operator)
+- [Ternary Operator In Java](https://www.baeldung.com/java-ternary-operator)
+- [The Modulo Operator in Java](https://www.baeldung.com/modulo-java)
+- [Java instanceof Operator](https://www.baeldung.com/java-instanceof)
+- [A Guide to Increment and Decrement Unary Operators in Java](https://www.baeldung.com/java-unary-operators)
+- [Java Compound Operators](https://www.baeldung.com/java-compound-operators)
+- [The XOR Operator in Java](https://www.baeldung.com/java-xor-operator)
+

core-java-modules/core-java-lang-operators/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>
+    <artifactId>core-java-lang-operators</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-lang-operators</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>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj-core.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-lang-operators</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <!-- testing -->
+        <assertj-core.version>3.10.0</assertj-core.version>
+    </properties>
+
+</project>

core-java-modules/core-java-lang-operators/src/main/java/com/baeldung/booleanoperators/Car.java

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+package com.baeldung.booleanoperators;
+
+public class Car {
+
+    private boolean diesel;
+    private boolean manual;
+
+    public Car(boolean diesel, boolean manual) {
+        this.diesel = diesel;
+        this.manual = manual;
+    }
+
+    public boolean isDiesel() {
+        return diesel;
+    }
+
+    public boolean isManual() {
+        return manual;
+    }
+
+    static Car dieselAndManualCar() {
+        return new Car(true, true);
+    }
+
+    static Car dieselAndAutomaticCar() {
+        return new Car(true, false);
+    }
+
+    static Car oilAndManualCar() {
+        return new Car(false, true);
+    }
+
+    static Car oilAndAutomaticCar() {
+        return new Car(false, false);
+    }
+}

core-java-modules/core-java-lang-operators/src/main/java/com/baeldung/keyword/Circle.java

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+package com.baeldung.keyword;
+
+public class Circle extends Round implements Shape {
+
+}

core-java-modules/core-java-lang-operators/src/main/java/com/baeldung/keyword/Ring.java

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+package com.baeldung.keyword;
+
+public class Ring extends Round {
+}

core-java-modules/core-java-lang-operators/src/main/java/com/baeldung/keyword/Round.java

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+package com.baeldung.keyword;
+
+public class Round {
+}

core-java-modules/core-java-lang-operators/src/main/java/com/baeldung/keyword/Shape.java

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+package com.baeldung.keyword;
+
+public interface Shape {
+}

core-java-modules/core-java-lang-operators/src/main/java/com/baeldung/keyword/Triangle.java

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+package com.baeldung.keyword;
+
+public class Triangle implements Shape {
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/booleanoperators/XorUnitTest.java

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+package com.baeldung.booleanoperators;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class XorUnitTest {
+
+    @Test
+    void givenDieselManualCar_whenXorOldSchool_thenFalse() {
+        Car car = Car.dieselAndManualCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isFalse();
+    }
+
+    @Test
+    void givenDieselAutomaticCar_whenXorOldSchool_thenTrue() {
+        Car car = Car.dieselAndAutomaticCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselManualCar_whenXorOldSchool_thenTrue() {
+        Car car = Car.oilAndManualCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselAutomaticCar_whenXorOldSchool_thenFalse() {
+        Car car = Car.oilAndAutomaticCar();
+        boolean dieselXorManual = (car.isDiesel() && !car.isManual()) || (!car.isDiesel() && car.isManual());
+        assertThat(dieselXorManual).isFalse();
+    }
+
+    @Test
+    void givenDieselManualCar_whenXor_thenFalse() {
+        Car car = Car.dieselAndManualCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isFalse();
+    }
+
+    @Test
+    void givenDieselAutomaticCar_whenXor_thenTrue() {
+        Car car = Car.dieselAndAutomaticCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselManualCar_whenXor_thenTrue() {
+        Car car = Car.oilAndManualCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isTrue();
+    }
+
+    @Test
+    void givenNonDieselAutomaticCar_whenXor_thenFalse() {
+        Car car = Car.oilAndAutomaticCar();
+        boolean dieselXorManual = car.isDiesel() ^ car.isManual();
+        assertThat(dieselXorManual).isFalse();
+    }
+    
+    @Test
+    void givenNumbersOneAndThree_whenXor_thenTwo() {
+        assertThat(1 ^ 3).isEqualTo(2);
+    }
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/compoundoperators/CompoundOperatorsUnitTest.java

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+package com.baeldung.compoundoperators;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class CompoundOperatorsUnitTest {
+
+    @Test
+    public void whenAssignmentOperatorIsUsed_thenValueIsAssigned() {
+        int x = 5;
+
+        assertEquals(5, x);
+    }
+
+    @Test
+    public void whenCompoundAssignmentUsed_thenSameAsSimpleAssignment() {
+        int a = 3, b = 3, c = -2;
+        a = a * c; // Simple assignment operator
+        b *= c; // Compound assignment operator
+
+        assertEquals(a, b);
+    }
+
+    @Test
+    public void whenAssignmentOperatorIsUsed_thenValueIsReturned() {
+        long x = 1;
+        long y = (x+=2);
+
+        assertEquals(3, y);
+        assertEquals(y, x);
+    }
+
+    @Test
+    public void whenCompoundOperatorsAreUsed_thenOperationsArePerformedAndAssigned() {
+        //Simple assignment
+        int x = 5; //x is 5
+
+        //Incrementation
+        x += 5; //x is 10
+        assertEquals(10, x);
+
+        //Decrementation
+        x -= 2; //x is 8
+        assertEquals(8, x);
+
+        //Multiplication
+        x *= 2; //x is 16
+        assertEquals(16, x);
+
+        //Division
+        x /= 4; //x is 4
+        assertEquals(4, x);
+
+        //Modulus
+        x %= 3; //x is 1
+        assertEquals(1, x);
+
+
+        //Binary AND
+        x &= 4; //x is 0
+        assertEquals(0, x);
+
+        //Binary exclusive OR
+        x ^= 4; //x is 4
+        assertEquals(4, x);
+
+        //Binary inclusive OR
+        x |= 8; //x is 12
+        assertEquals(12, x);
+
+
+        //Binary Left Shift
+        x <<= 2; //x is 48
+        assertEquals(48, x);
+
+        //Binary Right Shift
+        x >>= 2; //x is 12
+        assertEquals(12, x);
+
+        //Shift right zero fill
+        x >>>= 1; //x is 6
+        assertEquals(6, x);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void whenArrayIsNull_thenThrowNullException() {
+        int[] numbers = null;
+
+        //Trying Incrementation
+        numbers[2] += 5;
+    }
+
+    @Test(expected = ArrayIndexOutOfBoundsException.class)
+    public void whenArrayIndexNotCorrect_thenThrowArrayIndexException() {
+        int[] numbers = {0, 1};
+
+        //Trying Incrementation
+        numbers[2] += 5;
+    }
+
+    @Test
+    public void whenArrayIndexIsCorrect_thenPerformOperation() {
+        int[] numbers = {0, 1};
+
+        //Incrementation
+        numbers[1] += 5;
+        assertEquals(6, numbers[1]);
+    }
+
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/diamondoperator/Car.java

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+package com.baeldung.diamondoperator;
+
+public class Car<T extends Engine> implements Vehicle<T> {
+
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/diamondoperator/DiamondOperatorUnitTest.java

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+package com.baeldung.diamondoperator;
+
+import static org.junit.Assert.assertNotNull;
+
+import org.junit.Test;
+
+public class DiamondOperatorUnitTest {
+    @Test
+    public void whenCreateCarUsingDiamondOperator_thenSuccess() {
+        Car<Diesel> myCar = new Car<>();
+        assertNotNull(myCar);
+    }
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/diamondoperator/Diesel.java

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+package com.baeldung.diamondoperator;
+
+public class Diesel implements Engine {
+
+	@Override
+	public void start() {
+		System.out.println("Started Diesel...");
+	}
+
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/diamondoperator/Engine.java

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+package com.baeldung.diamondoperator;
+
+public interface Engine {
+
+	void start();
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/diamondoperator/Vehicle.java

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+package com.baeldung.diamondoperator;
+
+public interface Vehicle<T extends Engine> {
+
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/keyword/InstanceOfUnitTest.java

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+package com.baeldung.keyword;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.keyword.Circle;
+import com.baeldung.keyword.Ring;
+import com.baeldung.keyword.Round;
+import com.baeldung.keyword.Shape;
+import com.baeldung.keyword.Triangle;
+
+public class InstanceOfUnitTest {
+
+    @Test
+    public void giveWhenInstanceIsCorrect_thenReturnTrue() {
+        Ring ring = new Ring();
+        Assert.assertTrue("ring is instance of Round ", ring instanceof Round);
+    }
+
+    @Test
+    public void giveWhenObjectIsInstanceOfType_thenReturnTrue() {
+        Circle circle = new Circle();
+        Assert.assertTrue("circle is instance of Circle ", circle instanceof Circle);
+    }
+
+  
+    @Test
+    public void giveWhenInstanceIsOfSubtype_thenReturnTrue() {
+        Circle circle = new Circle();
+        Assert.assertTrue("circle is instance of Round", circle instanceof Round);
+    }
+
+    @Test
+    public void giveWhenTypeIsInterface_thenReturnTrue() {
+        Circle circle = new Circle();
+        Assert.assertTrue("circle is instance of Shape", circle instanceof Shape);
+    }
+    
+    @Test
+    public void giveWhenTypeIsOfObjectType_thenReturnTrue() {
+        Thread thread = new Thread();
+        Assert.assertTrue("thread is instance of Object", thread instanceof Object);
+    }
+
+    @Test
+    public void giveWhenInstanceValueIsNull_thenReturnFalse() {
+        Circle circle = null;
+        Assert.assertFalse("circle is instance of Round", circle instanceof Round);
+    }
+
+    @Test
+    public void giveWhenComparingClassInDiffHierarchy_thenCompilationError() {
+        // Assert.assertFalse("circle is instance of Triangle", circle instanceof Triangle);
+    }
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/modulo/ModuloUnitTest.java

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+package com.baeldung.modulo;
+
+import org.junit.Test;
+import static org.assertj.core.api.Java6Assertions.*;
+
+public class ModuloUnitTest {
+
+  @Test
+  public void whenIntegerDivision_thenLosesRemainder(){
+    assertThat(11 / 4).isEqualTo(2);
+  }
+
+  @Test
+  public void whenDoubleDivision_thenKeepsRemainder(){
+    assertThat(11 / 4.0).isEqualTo(2.75);
+  }
+
+  @Test
+  public void whenModulo_thenReturnsRemainder(){
+    assertThat(11 % 4).isEqualTo(3);
+  }
+
+  @Test(expected = ArithmeticException.class)
+  public void whenDivisionByZero_thenArithmeticException(){
+    double result = 1 / 0;
+  }
+
+  @Test(expected = ArithmeticException.class)
+  public void whenModuloByZero_thenArithmeticException(){
+    double result = 1 % 0;
+  }
+
+  @Test
+  public void whenDivisorIsOddAndModulusIs2_thenResultIs1(){
+    assertThat(3 % 2).isEqualTo(1);
+  }
+
+  @Test
+  public void whenDivisorIsEvenAndModulusIs2_thenResultIs0(){
+    assertThat(4 % 2).isEqualTo(0);
+  }
+
+  @Test
+  public void whenItemsIsAddedToCircularQueue_thenNoArrayIndexOutOfBounds(){
+    int QUEUE_CAPACITY= 10;
+    int[] circularQueue = new int[QUEUE_CAPACITY];
+    int itemsInserted = 0;
+    for (int value = 0; value < 1000; value++) {
+      int writeIndex = ++itemsInserted % QUEUE_CAPACITY;
+      circularQueue[writeIndex] = value;
+    }
+  }
+
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/ternaryoperator/TernaryOperatorUnitTest.java

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+package com.baeldung.ternaryoperator;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class TernaryOperatorUnitTest {
+
+    @Test
+    public void givenACondition_whenUsingTernaryOperator_thenItEvaluatesConditionAndReturnsAValue() {
+        int number = 10;
+        String msg = number > 10 ? "Number is greater than 10" : "Number is less than or equal to 10";
+
+        assertThat(msg).isEqualTo("Number is less than or equal to 10");
+    }
+
+    @Test
+    public void givenATrueCondition_whenUsingTernaryOperator_thenOnlyExpression1IsEvaluated() {
+        int exp1 = 0, exp2 = 0;
+        int result = 12 > 10 ? ++exp1 : ++exp2;
+
+        assertThat(exp1).isEqualTo(1);
+        assertThat(exp2).isEqualTo(0);
+        assertThat(result).isEqualTo(1);
+    }
+
+    @Test
+    public void givenAFalseCondition_whenUsingTernaryOperator_thenOnlyExpression2IsEvaluated() {
+        int exp1 = 0, exp2 = 0;
+        int result = 8 > 10 ? ++exp1 : ++exp2;
+
+        assertThat(exp1).isEqualTo(0);
+        assertThat(exp2).isEqualTo(1);
+        assertThat(result).isEqualTo(1);
+    }
+
+    @Test
+    public void givenANestedCondition_whenUsingTernaryOperator_thenCorrectValueIsReturned() {
+        int number = 6;
+        String msg = number > 10 ? "Number is greater than 10" : number > 5 ? "Number is greater than 5" : "Number is less than or equal to 5";
+
+        assertThat(msg).isEqualTo("Number is greater than 5");
+    }
+}

core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/unaryoperators/IncrementDecrementUnaryOperatorUnitTest.java

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+package com.baeldung.unaryoperators;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class IncrementDecrementUnaryOperatorUnitTest {
+
+    @Test
+    public void givenAnOperand_whenUsingPreIncrementUnaryOperator_thenOperandIsIncrementedByOne() {
+        int operand = 1;
+        ++operand;
+        assertThat(operand).isEqualTo(2);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPreIncrementUnaryOperatorInEvaluation_thenNumberIsIncrementedByOne() {
+        int operand = 1;
+        int number = ++operand;
+        assertThat(number).isEqualTo(2);
+    }
+
+    @Test
+    public void givenAnOperand_whenUsingPreDecrementUnaryOperator_thenOperandIsDecrementedByOne() {
+        int operand = 1;
+        --operand;
+        assertThat(operand).isEqualTo(0);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPreDecrementUnaryOperatorInEvaluation_thenNumberIsDecrementedByOne() {
+        int operand = 1;
+        int number = --operand;
+        assertThat(number).isEqualTo(0);
+    }
+
+    @Test
+    public void givenAnOperand_whenUsingPostIncrementUnaryOperator_thenOperandIsIncrementedByOne() {
+        int operand = 1;
+        operand++;
+        assertThat(operand).isEqualTo(2);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPostIncrementUnaryOperatorInEvaluation_thenNumberIsSameAsOldValue() {
+        int operand = 1;
+        int number = operand++;
+        assertThat(number).isEqualTo(1);
+    }
+
+    @Test
+    public void givenAnOperand_whenUsingPostDecrementUnaryOperator_thenOperandIsDecrementedByOne() {
+        int operand = 1;
+        operand--;
+        assertThat(operand).isEqualTo(0);
+    }
+
+    @Test
+    public void givenANumber_whenUsingPostDecrementUnaryOperatorInEvaluation_thenNumberIsSameAsOldValue() {
+        int operand = 1;
+        int number = operand--;
+        assertThat(number).isEqualTo(1);
+    }
+}