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Merge pull request #3239 from Wosin/BAEL-1367-variable-handles-demistyfied 

VarHandles
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Loredana Crusoveanu 2017-12-17 10:27:08 +02:00 committed by GitHub
parent 925297c60f ec95d9b208
commit 6592e4d179
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core-java-9/src/test/java/com/baeldung/java9/varhandles/VariableHandlesTest.java Normal file
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package com.baeldung.java9.varhandles;
import org.junit.Test;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import static org.assertj.core.api.Assertions.assertThat;
public class VariableHandlesTest {
public int publicTestVariable = 1;
private int privateTestVariable = 1;
public int variableToSet = 1;
public int variableToCompareAndSet = 1;
public int variableToGetAndAdd = 0;
public byte variableToBitwiseOr = 0;
@Test
public void whenVariableHandleForPublicVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
VarHandle publicIntHandle = MethodHandles
.lookup()
.in(VariableHandlesTest.class)
.findVarHandle(VariableHandlesTest.class, "publicTestVariable", int.class);
assertThat(publicIntHandle.coordinateTypes().size() == 1);
assertThat(publicIntHandle.coordinateTypes().get(0) == VariableHandles.class);
}
@Test
public void whenVariableHandleForPrivateVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
VarHandle privateIntHandle = MethodHandles
.privateLookupIn(VariableHandlesTest.class, MethodHandles.lookup())
.findVarHandle(VariableHandlesTest.class, "privateTestVariable", int.class);
assertThat(privateIntHandle.coordinateTypes().size() == 1);
assertThat(privateIntHandle.coordinateTypes().get(0) == VariableHandlesTest.class);
}
@Test
public void whenVariableHandleForArrayVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
VarHandle arrayVarHandle = MethodHandles
.arrayElementVarHandle(int[].class);
assertThat(arrayVarHandle.coordinateTypes().size() == 2);
assertThat(arrayVarHandle.coordinateTypes().get(0) == int[].class);
}
@Test
public void givenVarHandle_whenGetIsInvoked_ThenValueOfVariableIsReturned() throws NoSuchFieldException, IllegalAccessException {
VarHandle publicIntHandle = MethodHandles
.lookup()
.in(VariableHandlesTest.class)
.findVarHandle(VariableHandlesTest.class, "publicTestVariable", int.class);
assertThat((int) publicIntHandle.get(this) == 1);
}
@Test
public void givenVarHandle_whenSetIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
VarHandle publicIntHandle = MethodHandles
.lookup()
.in(VariableHandlesTest.class)
.findVarHandle(VariableHandlesTest.class, "variableToSet", int.class);
publicIntHandle.set(this, 15);
assertThat((int) publicIntHandle.get(this) == 15);
}
@Test
public void givenVarHandle_whenCompareAndSetIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
VarHandle publicIntHandle = MethodHandles
.lookup()
.in(VariableHandlesTest.class)
.findVarHandle(VariableHandlesTest.class, "variableToCompareAndSet", int.class);
publicIntHandle.compareAndSet(this, 1, 100);
assertThat((int) publicIntHandle.get(this) == 100);
}
@Test
public void givenVarHandle_whenGetAndAddIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
VarHandle publicIntHandle = MethodHandles
.lookup()
.in(VariableHandlesTest.class)
.findVarHandle(VariableHandlesTest.class, "variableToGetAndAdd", int.class);
int before = (int) publicIntHandle.getAndAdd(this, 200);
assertThat(before == 0);
assertThat((int) publicIntHandle.get(this) == 200);
}
@Test
public void givenVarHandle_whenGetAndBitwiseOrIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
VarHandle publicIntHandle = MethodHandles
.lookup()
.in(VariableHandlesTest.class)
.findVarHandle(VariableHandlesTest.class, "variableToBitwiseOr", byte.class);
byte before = (byte) publicIntHandle.getAndBitwiseOr(this, (byte) 127);
assertThat(before == 0);
assertThat(variableToBitwiseOr == 127);
}
}