public class CBank {
    private static int sum=0;
    public synchronized static void add(int n){            //ͬ
    	int tmp=sum;
    	tmp=tmp+n;
    	try{
    		Thread.sleep((int)(1000*Math.random()));     //С˯
    	}
    	catch(InterruptedException e){
    	}
    	sum=tmp;
    	System.out.println("sum="+sum);
    }
}
class CCustomer extends Thread{
	public void run(){
		for(int i=1;i<=3;i++)
			CBank.add(100);
	}
}
 class Syn_Thread{  
    public static void main(String[] args) {
//̶߳c1c2c1c2ͬһ
        CCustomer c1=new CCustomer();          
        CCustomer c2=new CCustomer();
        c1.start();
        c2.start();
    }
}
