java中sleep()和wait()區別

sleep()與wait()區別：

1. sleep()是Thread類的方法，wait()是Object類中的方法；
2. sleep()方法可以在任何地方使用，wait()方法只能在synchronized方法或者synchronized塊中使用
3. Thread.sleep()只會讓出cpu，不會導致鎖的行爲發生改變；
4. Object.wait()不僅讓出cpu,還會釋放已經佔有的同步資源鎖。

實例：

package com.gy;

public class Wait {
    final static Object obj = new Object();

    public static void main(String[] args) throws InterruptedException {
        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("Thread A is waiting to lock");
                synchronized (obj){
                    System.out.println("Thread A is locked");
                    try {
                        //等待2oms，讓出cpu，但是不會釋放鎖
                        Thread.sleep(20);
                        System.out.println("Thread A do wait method");
                        //讓出cpu,並且釋放鎖
                        obj.wait(20);
                        System.out.println("Thread A is done");
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();

        Thread.sleep(5);

        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("Thread B is waiting to lock");
                synchronized (obj){
                    System.out.println("Thread B is locked");
                    try {
                        System.out.println("Thread B is sleeping 20 ms");
                        Thread.sleep(20);
                        System.out.println("Thread B is done");
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }
}