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Commit af0db96

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Cristian Stancalau
committed
Fix review suggestions.
1 parent 6a82d1c commit af0db96

9 files changed

Lines changed: 125 additions & 94 deletions

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‎core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Animal.java‎

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package com.baeldung.exceptions.classcastexception;
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public interface Animal {
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String getName();
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}

‎core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Box.java‎

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package com.baeldung.exceptions.classcastexception;
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public class Box<T> {
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private T content;
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public T getContent() {
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return content;
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}
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public void setContent(T content) {
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this.content = content;
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}
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}

‎core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Frog.java‎

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package com.baeldung.exceptions.classcastexception;
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public class Frog extends Reptile {
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@Override
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public String getName() {
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return super.getName() + ": Frog";
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}
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}

‎core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Main.java‎

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‎core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Mammal.java‎

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package com.baeldung.exceptions.classcastexception;
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public class Mammal implements Animal {
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@Override
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public String getName() {
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return "Mammal";
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}
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}

‎core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Reptile.java‎

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package com.baeldung.exceptions.classcastexception;
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public class Reptile implements Animal {
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@Override
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public String getName() {
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return "Reptile";
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}
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}

‎core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/classcastexception/CheckedCastsUnitTest.java‎

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package com.baeldung.exceptions.classcastexception;
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import org.junit.Test;
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import java.io.Serializable;
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public class CheckedCastsUnitTest {
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@Test(expected = ClassCastException.class)
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public void givenBaseTypeVariableReferencingChildInstance_whenCastToIncompatibleSubtype_thenClassCastException() {
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Animal animal = new Frog();
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//A checked downcast to Mammal is incompatible from Frog because Frog is not a subtype of Mammal.
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Mammal mammal = (Mammal) animal;
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}
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@Test(expected = ClassCastException.class)
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public void givenBaseTypeVariableReferencingChildInstance_whenCastToIncompatibleInterface_thenClassCastException() {
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Animal animal = new Frog();
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//A checked cast to Serializable is incompatible from Frog because Frog is not a subtype of Serializable.
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Serializable serial = (Serializable) animal;
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}
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@Test(expected = ClassCastException.class)
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public void givenObjectVariableReferencingPrimitiveArray_whenCastToBoxedTypeArray_thenClassCastException() {
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Object primitives = new int[1];
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//A checked cast to Integer[] is incompatible from primitive arrays. Auto-boxing does not work for arrays.
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Integer[] integers = (Integer[]) primitives;
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}
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@Test(expected = ClassCastException.class)
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public void givenObjectVariableReferencingPrimitiveArray_whenCastToPromotedTypeArray_thenClassCastException() {
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Object primitives = new int[1];
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//A checked cast to long[] is incompatible from int[]. Type promotion does not work for arrays.
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long[] longs = (long[]) primitives;
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}
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}

‎core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/classcastexception/GenericConversionUnitTest.java‎

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package com.baeldung.exceptions.classcastexception;
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import org.junit.Test;
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public class GenericConversionUnitTest {
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@Test(expected = ClassCastException.class)
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public void givenIncompatibleType_whenConvertInstanceOfObject_thenClassCastException() {
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// Should have been null, but due to type erasure, inside convertInstanceOfObject,
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// it will attempt to cast to Object instead of String, so it casts to Object, which is always possible.
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String shouldBeNull = convertInstanceOfObject(123);
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}
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public static <T> T convertInstanceOfObject(Object o) {
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try {
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return (T) o; // Casts to Object due to type erasure
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} catch (ClassCastException e) {
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return null; // Will never reach this
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}
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}
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}

‎core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/classcastexception/UncheckedConversionUnitTest.java‎

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package com.baeldung.exceptions.classcastexception;
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import org.junit.Test;
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public class UncheckedConversionUnitTest {
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@Test(expected = ClassCastException.class)
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public void givenPollutedGenericType_whenGetProperty_thenClassCastException() {
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Box<Long> originalBox = new Box<>();
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Box raw = originalBox;
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raw.setContent(2.5);
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Box<Long> bound = (Box<Long>) raw;
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//An incompatible element was found in the raw box.
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Long content = bound.getContent();
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}
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}

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