Thread.join is not working

Question

I want to execute the following threads, and wait for them to finish in order to continue working, However, this is not achieved through my code and I don't know why, I suppose join should force the current thread to wait for all threads to finish!. I would be pleased if anyone could help me!

Here's my code:

ArrayList<Thread> retrievalThreads=new ArrayList<Thread>();

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getProfilePictures(false);
        }
    }));

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getNumVotesThisWeek();
        }
    }));

    retrievalThreads.add( new Thread(new Runnable() {
        @Override
        public void run() {
            getTotalVotes(true);
        }
    }));

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getTotalMatches();
        }
    }));

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getUserActivityLevel();
        }
    }));

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getUserMatchMakerLevel();
        }
    }));

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getLastBoostTimeStamp(true);
        }
    }));

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getLastStealTimeStamp(true);
        }
    }));

    retrievalThreads.add(new Thread(new Runnable() {
        @Override
        public void run() {
            getFacebookFriends();
        }
    }));

    //Start all above threads
    for (int i=0;i<retrievalThreads.size();i++)
        retrievalThreads.get(i).start();

    //Wait for them to finish
    for (int i=0;i<retrievalThreads.size();i++){
        try {
            retrievalThreads.get(i).join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    Log.i("Finished","TheAbove");

The printing in the Log Console is done before threads finish execution!

Yes, calling `join` will force the current thread to wait for all threads in `retrievalThreads` finish. And the code you posted is fine. Can you post more details? The "Log Console is done" before which method? — xingbin, Feb 24 '18 at 16:36
Printing is done before all threads finish @user6690200 , as if I didn't call join() — Ahmed Khairy, Feb 24 '18 at 16:45
I understand. But the code you post seems ok. Can you post more details? — xingbin, Feb 24 '18 at 16:58
How to create a Minimal, Complete, and Verifiable example? https://stackoverflow.com/help/mcve — xingbin, Feb 24 '18 at 17:05
@user6690200 the methods I'm executing inside the run() method are volley requests — Ahmed Khairy, Feb 24 '18 at 17:24
The code you have provided here looks fine. If you put a log message in each of your threads at the end of their run methods, you will see that join is working just fine. — Gray, Feb 26 '18 at 00:22

score 1 · Answer 1 · answered Feb 24 '18 at 17:36

1

Thread.join() will wait only for the thread which creates volley reuqest, not all threads. Volley will spawn other threads to send the request asynchronously. You need synchronous volley requests.

answered Feb 24 '18 at 17:36

xingbin

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Thread.join is not working

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