Java并发之不可思议的死循环详解

package com.zzj.concurrency;

public class VolatileObjectTest implements Runnable{
 private ObjectA objectA; // 加上volatile 就可以正常结束While循环了
  public VolatileObjectTest(ObjectA a) { 
    this.objectA = a; 
  } 
  
  public ObjectA getA() { 
    return objectA; 
  } 
  
  public void setA(ObjectA a) { 
    this.objectA = a; 
  } 
  
  @Override 
  public void run() { 
    long i = 0; 
    while (objectA.isFlag()) { 
      i++; 
    } 
    System.out.println("stop My Thread " + i); 
  } 
  
  public void stop() { 
    objectA.setFlag(false); 
  } 
  
  public static void main(String[] args) throws InterruptedException { 
     // 如果启动的时候加上-server 参数则会 输出 Java HotSpot(TM) Server VM 
    System.out.println(System.getProperty("java.vm.name")); 
      
    VolatileObjectTest test = new VolatileObjectTest(new ObjectA()); 
    new Thread(test).start(); 
  
    Thread.sleep(1000); 
    test.stop(); 
    System.out.println("Main Thread " + test.getA().isFlag()); 
  } 
  
  static class ObjectA { 
    private boolean flag = true; 
  
    public boolean isFlag() { 
      return flag; 
    } 
  
    public void setFlag(boolean flag) { 
      this.flag = flag; 
    } 
  
  } 
}

while (objectA.isFlag()) { 
    i++;
}

if(objectA.isFlag()){
  while(true){
    i++;
  }
}