多线程2

1.

public class MultiThread {
    private static int num = 0;
    
    public static synchronized void printNum(String tag){
        if("a".equals(tag)){
            System.out.println("tag a, set num over");
            num = 100;
        } else {
            System.out.println("tag b, set num over");
            num = 200;
        }
        System.out.println("tag:"+tag+",num=" + num);
    }

    public static void main(String[] args) {
        final MultiThread multiThread1 = new MultiThread();
        final MultiThread multiThread2 = new MultiThread();
        
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                multiThread1.printNum("a");
            }
        });
        
        Thread t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                multiThread2.printNum("b");
            }
        });
        
        t1.start();
        t2.start();
        
        /*
         *  tag a, set num over
            tag:a,num=100
            tag b, set num over
            tag:b,num=200
         */
    }
}