java多线程编程——线程同步之同步函数

class Save{
    private int sum;
    public synchronized void add(int n){
        sum+=n;
        System.out.println("sum="+sum);
    }
}
class Cus implements Runnable{
    private Save b=new Save();
    public void run(){
        for(int x=0;x<3;x++){
            b.add(100);
        }
    }
}
class Bank{
    public static void main(String[] args){
        Cus c=new Cus();
        Thread th1=new Thread(c);
        Thread th2=new Thread(c);
        th1.start();
        th2.start();
    }
}