Hello all,

I am having some troubles to understand how I have to stop a running thread. I'll try to explain it by example. Assume the following class:

public class MyThread extends Thread {
    protected volatile boolean running = true;

    public void run() {
        while (running) {
            synchronized (someObject) {
                while (someObject.someCondition() == false && running) {
                    try {
                        someObject.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                // do something useful with someObject
            }
        }
    }

    public void halt() {
        running = false;
        interrupt();
    }
}

Assume the thread is running and the following statement is evaluated to true:

while (someObject.someCondition() == false && running)

Then, another thread calls MyThread.halt(). Eventhough this function sets 'running' to false (which is a volatile boolean) and interrupts the thread, the following statement is still executed:

someObject.wait();

We have a deadlock. The thread will never be halted.

Then I came up with this, but I am not sure if it is correct:

public class MyThread extends Thread {
    protected volatile boolean running = true;

    public void run() {
        while (running) {
            synchronized (someObject) {
                while (someObject.someCondition() == false && running) {
                    try {
                        someObject.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                // do something useful with someObject
            }
        }
    }

    public void halt() {
        running = false;
        synchronized(someObject) {
            interrupt();
        }
    }
}

Is this correct? Is this the most common way to do this?

This seems like an obvious question, but I fail to come up with a solution. Thanks a lot for your help.