Question

I want to throw an exception from a runnable thread but its not possible to throw it from thread so can we pass the status(any exception ) of chlild thread to parent thread?.

I read about thread.join() but in this case parent thread waits untill child thread finishes its excecution.

In my case my parent thread start threads one by one after some period of time ,but when any thread throws exception ,it should notify the paent about the failure so that parent thread does not start other threads.

is there any way to implement it ? can anyone help me do solve this.

Answer 1

To elaborate on @zeller’s answer, you could do something like the following construct:

//Use a Callable instead of Runnable to be able to throw your exception
Callable<Void> c = new Callable<Void> () {
    public Void call() throws YourException {
        //run your task here which can throw YourException
        return null;
    }
}

//Use an ExecutorService to manage your threads and monitor the futures
ExecutorService executor = Executors.newCachedThreadPool();
List<Future> futures = new ArrayList<Future> ();

//Submit your tasks (equivalent to new Thread(c).start();)
for (int i = 0; i < 5; i++) {
    futures.add(executor.submit(c));
}

//Monitor the future to check if your tasks threw exceptions
for (Future f : futures) {
    try {
        f.get();
    } catch (ExecutionException e) {
        //encountered an exception in your task => stop submitting tasks
    }
}