abstract class ThreadMemo implements Runnable {
    private Thread t;
    protected String threadName;

    // public static int var = 0;
    volatile public static int var = 0; // 只需要新增volatile關鍵字就可以了

    public ThreadMemo(String name) {
        threadName = name;
        System.out.println("Creating " + threadName);
    }

    abstract public void run();

    public void start() {
        System.out.println("Starting " + threadName);
        if (t == null) {
            t = new Thread(this, threadName);
            t.start();
        }
    }

}

class MyThread extends ThreadMemo {

    MyThread(String name) {
        super(name);
    }

    public void run() {
        var = super.var;
        while(true) {
            var = var + 1;
            // sleep(50);
            // time.sleep(50);
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                System.out.println("Thread " + threadName + " interrupted.");
            }
            // System.out.println("mythread 1 var: " + var);
        }
        
    }
}

class MyThread2 extends ThreadMemo {

    MyThread2(String name) {
        super(name);
    }

    public void run() {
        var = super.var;
        while(true) {
            if(var < 10) {
                // try {
                //     Thread.sleep(1);
                // } catch (InterruptedException e) {
                //     System.out.println("Thread " + threadName + " interrupted.");
                // }
                // Object o = new Object();

                continue;
            } 
            System.out.println("mythread2 var = " + var);
            break;
        }
    }
}



public class Test2 {
    // public static int var = 0;
    public static void main(String[] args) {
        ThreadMemo t1 = new MyThread("Thread-1");
        ThreadMemo t2 = new MyThread2("Thread-2");

        Thread a = new Thread(t1);
        Thread b = new Thread(t2);
        a.start();
        b.start();
    }
}