yield()方法的作用放弃当前的cpu资源，将他让给其他的任务去占用cpu的执行时间，但放弃的时间不确定，有可能刚放弃，马上又获得cpu时间片
测试
1 package com.cky.thread; 2 3 /** 4 * Created by edison on 2017/12/3. 5 */ 6 public class MyThread3 extends Thread{ 7 @Override 8 public void run() { 9 super.run(); 10 long begin = System.currentTimeMillis(); 11 int count =0; 12 for (int i = 0; i < 5000000; i++) { 13 //Thread.yield(); 14 count=count+(i+1); 15 } 16 long end = System.currentTimeMillis(); 17 System.out.println("用时" +(end-begin)+"毫秒"); 18 } 19 }
1 package com.cky.test; 2 3 import com.cky.thread.MyThread3; 4 5 /** 6 * Created by edison on 2017/12/3. 7 */ 8 public class Test3 { 9 public static void main(String[] args) { 10 MyThread3 th = new MyThread3(); 11 th.start(); 12 } 13 }
package com.cky.thread; /** * Created by edison on 2017/12/3. */ public class MyThread3 extends Thread{ @Override public void run() { super.run(); long begin = System.currentTimeMillis(); int count =0; for (int i = 0; i < 5000000; i++) { Thread.yield(); count=count+(i+1); } long end = System.currentTimeMillis(); System.out.println("用时" +(end-begin)+"毫秒"); } }
上述两种情况运行结果
有注释：48毫秒
无注释：11100毫秒
结果说明了他放弃当前的cpu资源。