i++操作非原子的验证代码
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1 package incre; 2 3 public class Incre { 4 public static void main(String[] args) { 5 class Count implements Runnable { 6 public int num; 7 @Override 8 public void run() { 9 //自增操作,非原子操作,线程不安全 10 // for (int i = 0; i < 10000; i++) { 11 // num++; 12 // } 13 14 //对代码进行同步,查看正确结果。 15 synchronized (this) { 16 for (int i = 0; i < 10000; i++) { 17 num++; 18 } 19 } 20 } 21 22 public int getNum(){ 23 return num; 24 } 25 } 26 27 Count c = new Count(); 28 29 //创建多个线程 30 final int THREAD_COUNT = 10; 31 Thread[] threadArray = new Thread[THREAD_COUNT]; 32 for(int i = 0; i < threadArray.length; i++){ 33 threadArray[i] = new Thread(c); 34 } 35 36 //启动多个线程 37 for(Thread t : threadArray){ 38 t.start(); 39 } 40 41 //等待这些线程结束 42 for(Thread t : threadArray){ 43 try { 44 t.join(); 45 } catch (InterruptedException e) { 46 e.printStackTrace(); 47 } 48 } 49 50 //查看计数结果 51 System.out.println("计数结果:" + c.getNum()); 52 } 53 }