java.lang.Object作为所有类的基础类，java默认所有类都是Object的子类

静态块

static {        registerNatives();    }

属性：

native方法：

静态方法：

private static native void registerNatives();

1、获取类名

public final native Class
     getClass();

2、获取hashCode，不同对象实例具有相同的hashCode，Object类的hashCode()方法返回这个对象存储的内存地址的编号。

public native int hashCode();

3、equals方法：判断对象是否是同一个对象

public boolean equals(Object obj) {    return (this == obj);}

4、clone方法，复制对象

protected native Object clone() throws CloneNotSupportedException;

6、线程唤醒

public final native void notify();public final native void notifyAll();

7、线程等待

public final native void wait(long timeout) throws InterruptedException;

8、finalize方法，垃圾回收时调用方法

protected void finalize() throws Throwable { }

9、toString()

public String toString() {        return getClass().getName() + "@" + Integer.toHexString(hashCode());}

public class ThreadF { public static void main(String[] args) { final Object object = new Object();        Thread t1 = new Thread() {            public void run()            {                synchronized (object) {                    System.out.println("T1 start!");                    try {                        object.wait();                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                    System.out.println("T1 end!");                }            }        };        Thread t2 = new Thread() {            public void run()            {                synchronized (object) {                    System.out.println("T2 start!");                    object.notify();                    System.out.println("T2 end!");                }            }        };        Thread t3 = new Thread() {         public void run()         {          synchronized (object) {           System.out.println("T3 start!");           object.notify();           System.out.println("T3 end!");          }         }        };        Thread t4 = new Thread() {            public void run()            {                synchronized (object) {                    System.out.println("T4 start!");                    try {                        object.wait();                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                    System.out.println("T4 end!");                }            }        };        t1.start();        t2.start();        t3.start();        t4.start();       }}