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[instanceOf-stream] Checking instanceof in Java Stream (#13419)

This commit is contained in:
Kai Yuan 2023-02-04 17:12:16 +01:00 committed by GitHub
parent a70afe6a9f
commit c0be80a64a
1 changed files with 35 additions and 23 deletions
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58
core-java-modules/core-java-lang-operators/src/test/java/com/baeldung/keyword/InstanceOfUnitTest.java
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@ -1,55 +1,67 @@
package com.baeldung.keyword; package com.baeldung.keyword;
import org.junit.Assert;
import org.junit.jupiter.api.Test; import org.junit.jupiter.api.Test;
import com.baeldung.keyword.Circle; import java.util.List;
import com.baeldung.keyword.Ring; import java.util.stream.Collectors;
import com.baeldung.keyword.Round; import java.util.stream.Stream;
import com.baeldung.keyword.Shape;
import com.baeldung.keyword.Triangle; import static org.junit.jupiter.api.Assertions.*;
public class InstanceOfUnitTest { public class InstanceOfUnitTest {
@Test @Test
public void giveWhenInstanceIsCorrect_thenReturnTrue() { void giveWhenInstanceIsCorrect_thenReturnTrue() {
Ring ring = new Ring(); Ring ring = new Ring();
Assert.assertTrue("ring is instance of Round ", ring instanceof Round); assertTrue(ring instanceof Round);
} }
@Test @Test
public void giveWhenObjectIsInstanceOfType_thenReturnTrue() { void giveWhenObjectIsInstanceOfType_thenReturnTrue() {
Circle circle = new Circle(); Circle circle = new Circle();
Assert.assertTrue("circle is instance of Circle ", circle instanceof Circle); assertTrue(circle instanceof Circle);
} }
@Test @Test
public void giveWhenInstanceIsOfSubtype_thenReturnTrue() { void giveWhenInstanceIsOfSubtype_thenReturnTrue() {
Circle circle = new Circle(); Circle circle = new Circle();
Assert.assertTrue("circle is instance of Round", circle instanceof Round); assertTrue(circle instanceof Round);
} }
@Test @Test
public void giveWhenTypeIsInterface_thenReturnTrue() { void giveWhenTypeIsInterface_thenReturnTrue() {
Circle circle = new Circle(); Circle circle = new Circle();
Assert.assertTrue("circle is instance of Shape", circle instanceof Shape); assertTrue(circle instanceof Shape);
} }
@Test @Test
public void giveWhenTypeIsOfObjectType_thenReturnTrue() { void giveWhenTypeIsOfObjectType_thenReturnTrue() {
Thread thread = new Thread(); Thread thread = new Thread();
Assert.assertTrue("thread is instance of Object", thread instanceof Object); assertTrue(thread instanceof Object);
} }
@Test @Test
public void giveWhenInstanceValueIsNull_thenReturnFalse() { void giveWhenInstanceValueIsNull_thenReturnFalse() {
Circle circle = null; Circle circle = null;
Assert.assertFalse("circle is instance of Round", circle instanceof Round); assertFalse(circle instanceof Round);
} }
@Test @Test
public void giveWhenComparingClassInDiffHierarchy_thenCompilationError() { void giveWhenComparingClassInDiffHierarchy_thenCompilationError() {
// Assert.assertFalse("circle is instance of Triangle", circle instanceof Triangle); //assertFalse( circle instanceof Triangle);
} }
}
@Test
void giveWhenStream_whenCastWithoutInstanceOfChk_thenGetException() {
Stream<Round> roundStream = Stream.of(new Ring(), new Ring(), new Circle());
assertThrows(ClassCastException.class, () -> roundStream.map(it -> (Ring) it).collect(Collectors.toList()));
}
@Test
void giveWhenStream_whenCastAfterInstanceOfChk_thenGetExpectedResult() {
Stream<Round> roundStream = Stream.of(new Ring(), new Ring(), new Circle());
List<Ring> ringList = roundStream.filter(it -> it instanceof Ring).map(it -> (Ring) it).collect(Collectors.toList());
assertEquals(2, ringList.size());
}
}