Unsafe测试，实现缺省参数构造

package com.graker.unsafe.demos;

import org.junit.Test;
import sun.misc.Unsafe;

import java.lang.reflect.Field;

class OtherObject {
    private int x;
    public OtherObject(int x) {
        this.x = x;
    }

    @Override
    public String toString() {
        return "OtherObject{" +
                "x=" + x +
                '}';
    }
}
class SomeObject {
    private OtherObject id;
    private OtherObject obj;
    public SomeObject(OtherObject i) throws NoSuchFieldException, IllegalAccessException {
        Unsafe theUnsafe = UnsafeLoader.getUnsafe();
        System.out.println(this.id);

        if (i != null)
            this.id = i;
        else {
            long SomeObject_idOffset = theUnsafe.objectFieldOffset(SomeObject.class.getDeclaredField("id"));

            boolean ModifiedSuccess = theUnsafe.compareAndSwapObject(this,SomeObject_idOffset,null,new OtherObject(100));
            System.out.println(this.id);
            System.out.println(ModifiedSuccess);
        }
    }

    @Override
    public String toString() {
        return "SomeObject{" +
                "id=" + id +
                ", obj=" + obj +
                '}';
    }
}
public class TestUnsafe {

    @Test
    public void testUnsafe() throws NoSuchFieldException, IllegalAccessException {
        SomeObject someObject = new SomeObject(null);
        System.out.print(someObject);
    }
}

package com.graker.unsafe.demos;

import sun.misc.Unsafe;

import java.lang.reflect.Field;

public class UnsafeLoader {
    private static Unsafe theUnsafe;
    private volatile static boolean inited = false;

    public UnsafeLoader() {
    }

    public static Unsafe getUnsafe() throws NoSuchFieldException, IllegalAccessException {
        // balking
        if(!inited) {
            synchronized (UnsafeLoader.class) {
                if (!inited) {
                    Field Declared = Unsafe.class.getDeclaredField("theUnsafe");
                    Declared.setAccessible(true);
                    theUnsafe = (Unsafe) Declared.get(Unsafe.class);
                    inited = true;
                }
            }
        }
        return theUnsafe;
    }
}