Add FinalTest to ensure the compiler in-lining behavior does not change in the future
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package com.moparisthebest.jdbc;
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import com.moparisthebest.jdbc.dto.FinalDTO;
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import org.junit.Before;
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import org.junit.Test;
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import static org.junit.Assert.assertTrue;
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import static org.junit.Assert.assertFalse;
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/**
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* This test ensures the way the java compiler in-lines final variables today
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* is the same way it will in-line them tomorrow, since changes in this behavior
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* might silently break classes that are filled with reflection.
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*/
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public class FinalTest {
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private FinalDTO object;
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@Before
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public void before(){
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object = new FinalDTO();
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assertTrue(object.directEqualsReflection());
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}
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@Test
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public void testFinalPrimitiveLongDirectCantBeSet() {
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assertFalse(object.setField("finalPrimitiveLongDirect", 1L));
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}
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@Test
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public void testFinalStringDirectCantBeSet() {
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assertFalse(object.setField("finalStringDirect", "1"));
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}
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@Test
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public void testEffectiveFinalPrimitiveLongDirectCanBeSet() {
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assertTrue(object.setField("effectiveFinalPrimitiveLongDirect", 1L));
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}
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@Test
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public void testEffectiveFinalStringDirectCanBeSet() {
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assertTrue(object.setField("effectiveFinalStringDirect", "1"));
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}
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@Test
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public void testFinalPrimitiveLongConstructorCanBeSet() {
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assertTrue(object.setField("finalPrimitiveLongConstructor", 1L));
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}
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@Test
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public void testFinalStringConstructorCanBeSet() {
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assertTrue(object.setField("finalStringConstructor", "1"));
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}
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@Test
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public void testFinalLongDirectCanBeSet() {
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assertTrue(object.setField("finalLongDirect", 1L));
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}
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@Test
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public void testFinalLongConstructorCanBeSet() {
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assertTrue(object.setField("finalLongConstructor", 1L));
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}
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}
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package com.moparisthebest.jdbc.dto;
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import sun.misc.Unsafe;
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import java.lang.reflect.Field;
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import java.util.Objects;
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/**
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* This class is meant to test the java compiler's in-lining behavior for final variables
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*/
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public class FinalDTO {
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private static final boolean useReflectionNotUnsafe = true;
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private final long finalPrimitiveLongDirect = 2L;
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private long effectiveFinalPrimitiveLongDirect = 2L;
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private final long finalPrimitiveLongConstructor;
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{
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this.finalPrimitiveLongConstructor = 2L;
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}
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private final String finalStringDirect = "2";
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private String effectiveFinalStringDirect = "2";
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private final String finalStringConstructor;
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{
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this.finalStringConstructor = "2";
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}
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private final Long finalLongDirect = 2L;
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private final Long finalLongConstructor;
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{
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this.finalLongConstructor = 2L;
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}
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public long getFinalPrimitiveLongDirect() {
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return finalPrimitiveLongDirect;
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}
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public long getEffectiveFinalPrimitiveLongDirect() {
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return effectiveFinalPrimitiveLongDirect;
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}
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public long getFinalPrimitiveLongConstructor() {
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return finalPrimitiveLongConstructor;
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}
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public String getFinalStringDirect() {
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return finalStringDirect;
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}
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public String getEffectiveFinalStringDirect() {
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return effectiveFinalStringDirect;
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}
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public String getFinalStringConstructor() {
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return finalStringConstructor;
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}
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public Long getFinalLongDirect() {
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return finalLongDirect;
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}
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public Long getFinalLongConstructor() {
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return finalLongConstructor;
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}
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@Override
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public String toString() {
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return "FinalTest{" +
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"finalPrimitiveLongDirect=" + finalPrimitiveLongDirect +
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", reflection finalPrimitiveLongDirect=" + getField("finalPrimitiveLongDirect") +
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", effectiveFinalPrimitiveLongDirect=" + effectiveFinalPrimitiveLongDirect +
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", reflection effectiveFinalPrimitiveLongDirect=" + getField("effectiveFinalPrimitiveLongDirect") +
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", finalPrimitiveLongConstructor=" + finalPrimitiveLongConstructor +
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", reflection finalPrimitiveLongConstructor=" + getField("finalPrimitiveLongConstructor") +
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", finalStringDirect=" + finalStringDirect +
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", reflection finalStringDirect=" + getField("finalStringDirect") +
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", effectiveFinalStringDirect=" + effectiveFinalStringDirect +
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", reflection effectiveFinalStringDirect=" + getField("effectiveFinalStringDirect") +
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", finalStringConstructor=" + finalStringConstructor +
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", reflection finalStringConstructor=" + getField("finalStringConstructor") +
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", finalLongDirect=" + finalLongDirect +
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", reflection finalLongDirect=" + getField("finalLongDirect") +
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", finalLongConstructor=" + finalLongConstructor +
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", reflection finalLongConstructor=" + getField("finalLongConstructor") +
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'}';
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}
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public boolean directEqualsReflection() {
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return directEqualsReflection(finalPrimitiveLongDirect, "finalPrimitiveLongDirect")
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&& directEqualsReflection(effectiveFinalPrimitiveLongDirect, "effectiveFinalPrimitiveLongDirect")
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&& directEqualsReflection(finalPrimitiveLongConstructor, "finalPrimitiveLongConstructor")
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&& directEqualsReflection(finalStringDirect, "finalStringDirect")
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&& directEqualsReflection(effectiveFinalStringDirect, "effectiveFinalStringDirect")
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&& directEqualsReflection(finalStringConstructor, "finalStringConstructor")
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&& directEqualsReflection(finalLongDirect, "finalLongDirect")
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&& directEqualsReflection(finalLongConstructor, "finalLongConstructor")
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;
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}
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private boolean directEqualsReflection(final Object object, final String fieldName) {
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return Objects.equals(object, getField(fieldName));
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}
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public Object getField(final String fieldName) {
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return getField(this, fieldName);
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}
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public boolean setField(final String fieldName, final Object fieldValue) {
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setField(this, fieldName, fieldValue);
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return directEqualsReflection();
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}
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private static Object getField(final Object object, final String fieldName) {
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try {
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final Field field = object.getClass().getDeclaredField(fieldName);
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if (useReflectionNotUnsafe) {
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field.setAccessible(true);
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return field.get(object);
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} else {
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final Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
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unsafeField.setAccessible(true);
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final Unsafe unsafe = (Unsafe) unsafeField.get(null);
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final long offset = unsafe.objectFieldOffset(field);
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if (field.getType().isPrimitive()) {
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if (field.getType().equals(long.class))
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return unsafe.getLong(object, offset);
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else
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throw new RuntimeException("unsupported primitive type");
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} else
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return unsafe.getObject(object, offset);
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}
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} catch (Throwable e) {
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throw new RuntimeException(e);
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}
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}
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private static void setField(final Object object, final String fieldName, final Object fieldValue) {
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try {
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final Field field = object.getClass().getDeclaredField(fieldName);
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if (useReflectionNotUnsafe) {
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field.setAccessible(true);
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field.set(object, fieldValue);
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} else {
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final Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
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unsafeField.setAccessible(true);
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final Unsafe unsafe = (Unsafe) unsafeField.get(null);
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final long offset = unsafe.objectFieldOffset(field);
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if (field.getType().isPrimitive()) {
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if (fieldValue instanceof Long)
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unsafe.putLong(object, offset, (Long) fieldValue);
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else
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throw new RuntimeException("unsupported primitive type");
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} else
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unsafe.putObject(object, offset, fieldValue);
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}
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} catch (Throwable e) {
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throw new RuntimeException(e);
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}
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}
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public static void main(final String[] args) {
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final FinalDTO object = new FinalDTO();
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System.out.println("1: " + object);
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setField(object, "finalPrimitiveLongDirect", 1L);
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System.out.println("2: " + object);
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setField(object, "finalPrimitiveLongConstructor", 1L);
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System.out.println("3: " + object);
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setField(object, "finalStringDirect", "1");
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System.out.println("4: " + object);
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setField(object, "finalStringConstructor", "1");
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System.out.println("5: " + object);
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setField(object, "finalLongDirect", 1L);
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System.out.println("6: " + object);
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setField(object, "finalLongConstructor", 1L);
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System.out.println("7: " + object);
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setField(object, "effectiveFinalPrimitiveLongDirect", 1L);
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System.out.println("8: " + object);
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setField(object, "effectiveFinalStringDirect", "1");
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System.out.println("9: " + object);
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}
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}
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