wait() and sleep() - looking for suggestions

[mari bo]

Hi guys, nice to be here again!

I have a little question about threads. I have a project where there is a thread which
is doing something, and that "doing something" is simulated by sleep().
I have to implement a way to stop for a moment that "doing something" by a wait() call,
time in which the thread would save its state(to be implemented in a second moment).

I tried to implement that in the following way:

public class Threading {

	public static void main(String[]args)throws InterruptedException {
		
		
		ThreadA a = new ThreadA();
		a.start();
		
		synchronized(a){
			System.out.println("a: wait calling");
			a.wait();
			System.out.println("a: now while again...");
		}
	}
}

class ThreadA extends Thread {
	
	public void run() {
		
		while(true){
			
			try {
				System.out.println("a: sleeping 5 sec...");
				sleep(5000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			
			if (12 % (int)(Math.random()*10+1) == 0){ 
				synchronized (this){
					System.out.println("a: stop the sleeping");
					
					try {
						sleep(2000);  // it simulates the time used to save the state
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
					System.out.println("a: now way back to main");
					notify();

				}
			}
			
			System.out.println("a: another while round!");
		}
		
	}
}

Actually, it doesn't stop the 5 seconds sleeping, but it waits for the sleep to finish and then it simulates the stopping.
My question is:

do you know a nice way to tell the sleeping to stop with the wait() calling?

Thank you very much for your attention!

maribo

[Nomaan Butt]

this is quite old post but still i would like to answer,

I have to implement a way to stop for a moment that "doing something" by a wait() call,
time in which the thread would save its state(to be implemented in a second moment).

if i have understood correctly then the query is you need to stop for all the threads to finish and then save their states.

this can be done using CyclicBarrier. If i have understood the query correctly.

[Steve Luke]

"do you know a nice way to tell the sleeping to stop with the wait() calling?"

You can't get sleep() to stop with a wait() call, you need to interrupt the Thread which is sleeping.

public class Threading {

	public static void main(String[]args)throws InterruptedException {
		
		
		ThreadA a = new ThreadA();
		a.start();
		
		synchronized(a){
			System.out.println("a: wait calling");
			a.interrupt();
			a.wait();
			System.out.println("a: now while again...");
		}
	}
}

In this case, you probably would not want to print the stack trace when you catch the InterruptedException in ThreadA's run() method. Since the InterruptedException happens as a side effect of normal operation you would just catch the error and do nothing:

			
			try {
				System.out.println("a: sleeping 5 sec...");
				sleep(5000);
			} catch (InterruptedException e) {
				//I expect to get interrupted as a signal to do the saving.
			}