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Merge pull request #11223 from lsieun/master 

BAEL-5122: Add new section on instanceof
This commit is contained in:
Greg 2021-09-21 16:15:50 -04:00 committed by GitHub
parent 9d0330197c 28d708a2fa
commit e4a5b01840
1 changed files with 62 additions and 12 deletions
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54
core-java-modules/core-java-lang-3/src/test/java/com/baeldung/isinstancevsisassignablefrom/IsInstanceIsAssignableFromUnitTest.java
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@ -8,7 +8,30 @@ import org.junit.Test;
public class IsInstanceIsAssignableFromUnitTest { public class IsInstanceIsAssignableFromUnitTest {
@Test @Test
public void whenUsingIsInstanceProperly_desiredResultsHappen() { public void whenUsingInstanceOfProperly_thenDesiredResultsHappen() {
Shape shape = new Triangle();
Triangle triangle = new Triangle();
IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle();
Shape nonspecificShape = null;
assertTrue(shape instanceof Shape);
assertTrue(triangle instanceof Shape);
assertTrue(isoscelesTriangle instanceof Shape);
assertFalse(nonspecificShape instanceof Shape);
assertTrue(shape instanceof Triangle);
assertTrue(triangle instanceof Triangle);
assertTrue(isoscelesTriangle instanceof Triangle);
assertFalse(nonspecificShape instanceof Triangle);
assertFalse(shape instanceof IsoscelesTriangle);
assertFalse(triangle instanceof IsoscelesTriangle);
assertTrue(isoscelesTriangle instanceof IsoscelesTriangle);
assertFalse(nonspecificShape instanceof IsoscelesTriangle);
}
@Test
public void whenUsingIsInstanceProperly_thenDesiredResultsHappen() {
Shape shape = new Triangle(); Shape shape = new Triangle();
Triangle triangle = new Triangle(); Triangle triangle = new Triangle();
IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle(); IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle();
@ -33,7 +56,7 @@ public class IsInstanceIsAssignableFromUnitTest {
} }
@Test @Test
public void whenUsingIsAssignableFromProperly_desiredResultsHappen() { public void whenUsingIsAssignableFromProperly_thenDesiredResultsHappen() {
Shape shape = new Triangle(); Shape shape = new Triangle();
Triangle triangle = new Triangle(); Triangle triangle = new Triangle();
IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle(); IsoscelesTriangle isoscelesTriangle = new IsoscelesTriangle();
@ -64,4 +87,31 @@ public class IsInstanceIsAssignableFromUnitTest {
assertTrue(isoscelesTriangle2.getClass().isAssignableFrom(isoscelesTriangle2.getClass())); assertTrue(isoscelesTriangle2.getClass().isAssignableFrom(isoscelesTriangle2.getClass()));
} }
@Test(expected = NullPointerException.class)
public void whenUsingNull_thenDesiredResultsHappen() {
assertFalse(null instanceof Shape);
assertFalse(Shape.class.isInstance(null));
assertFalse(Shape.class.isAssignableFrom(null)); // NullPointerException
}
@Test
public void whenUsingPrimitiveType_thenDesiredResultsHappen() {
//assertFalse(10 instanceof int); // illegal
assertFalse(int.class.isInstance(10));
assertTrue(Integer.class.isInstance(10));
assertTrue(int.class.isAssignableFrom(int.class));
assertFalse(float.class.isAssignableFrom(int.class));
}
@Test
public void whenUsingClassInstanceVariable_thenDesiredResultsHappen() {
Shape shape = new Triangle();
Triangle triangle = new Triangle();
Class<?> clazz = shape.getClass();
//assertFalse(triangle instanceof clazz); // illegal
assertTrue(clazz.isInstance(triangle));
assertTrue(clazz.isAssignableFrom(triangle.getClass()));
}
} }