Question

I have an application that is redirecting my System.out text to a Jtextarea. This works fine but when I call one of the methods in my application is creates multiple threads and uses a latch counter to wait for them to finish. That method then calls latch.await() so that it does not finish running its code until the other threads are finished. The problem is that once the latch.await() code is called my JtextArea stops posting text until all the threads have finished. Any ideas around this? Eclipse console is able to keep posting while the latch.await() is running so it has to be possible.

Example:
From the GUI:

btnStart.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
System.out.println("You pressed Start");
MyGoogleSearch startParsing = new MyGoogleSearch();
try {
startParsing.startParser(othoSelection); ...

MyGoogleSearch:

Enumeration e = hm.elements();



    //Read in src/Ontology/Ontology.txt
    //Put each line into the searchQuery ArrayQueue
        while ((strLine = br.readLine()) != null)   
        {  
            searchQuery.put(strLine);
        }
        System.out.println("Finsihed loading");

        //Create 32 threads (More threads allows you to pull data from Bing faster.  Any more than 32 and Bing errors out (you start to pull data
        //too fast)
            for(int i = 0; i < 32; i++)
            {
                System.out.println("Starting thread: " + i);
                new NewThread();
            }

    //Wait for all of the threads to finish
    latch.await();
    e = hm.keys();

    //Write the URL's from the hashmap to a file
        while (e.hasMoreElements())
        {
            out.write(e.nextElement() + "\n");
        }

        //close input/output stream
        in.close();
        out.close();
        System.out.println("Done");

and the Thread does some stuff then

MyGoogleSearch.latch.countDown();

Answer 1

This works fine but when I call one of the methods in my application is creates multiple threads and uses a latch counter to wait for them to finish.

You could get around that by calling the method in a separate thread. However, I suspect the method is waiting for all the threads to complete because it wants to aggregate some results and then return the aggregated result (or something similar). If that’s the case, then there are several ways to deal with it, but probably the one that will make the most sense for a graphical application is to have the thread invoke a callback with any results which were obtained from the method.

If you post some sample code, then we can provide you with more specific answers and examples of how to do it.

Update:

I’m having a hard time reading your code, but I presume that ‘startParser’ is the call that’s blocking. Additionally, it doesn’t appear that the UI needs to wait for the results so I would recommend you do the simplest thing possible:

MyGoogleSearch startParsing = new MyGoogleSearch();

Thread t = new Thread(new Runnable(){
    public void run(){
        startParsing.startParser(othoSelection);
    }
}

// don't wait for this thread to finish
t.start();