线程不能同时执行

Question

I have three threads, each thread have to do some manipulation with the instance(q) of same class (Q), periodically (That's why I use Thread.sleep() in the method somecheck). Main task is to make thread execute not at the same time, so at one time can execute only one thread. I tried to put content of run method each thread into synchronized (q){}, but I do not understand where to put notify and wait methods.

class Q {
        boolean somecheck(int threadSleepTime){
        //somecheck__section, if I want to stop thread - return false;

            try{
            Thread.sleep(threadSleepTime);
            } catch (InterruptedException e) {                
            }
            return true;
        }
}



class threadFirst extends Thread  {
    private Q q;
    threadFirst(Q q){this.q=q;}

    public void run(){
        do{
            //Working with object of class Q
        }
        while(q.somecheck(10));
    }
}

class threadSecond extends Thread  {
    private Q q;
    threadSecond(Q q){this.q=q;}

    public void run(){
        do{
            //Working with object of class Q
        }
        while(q.somecheck(15));
    }
}

class threadThird extends Thread  {

    private Q q;
    threadThird(Q q){this.q=q;}

    public void run(){
        do{
            //Working with object of class Q
        }
        while(q.somecheck(20));
    }
}

class run{
    public static void main(String[] args) {
        Q q = new Q();
        threadFirst t1 = new threadFirst(q);
        threadSecond t2 = new threadSecond(q);
        threadThird t3 = new threadThird(q);
        t1.start();
        t2.start();
        t3.start();
    }
}

Answer 1

You don't need to put any notify() and wait() methods if you use synchronized blocks inside all of the methods, for example:

class threadFirst extends Thread {
    ...
    public void run() {
        synchronized (q) {
            //your loop here
        }
    }
    ...
}