CountDownLatch issue in android

Question

I am using countdownlatch as in example below. Here BackgroundDataPopulator creates an AyncTask which in turn invokes displayData in PackagePopulator. But it never happens and the activity gets stuck. What am I doing wrong here.

public class PackagePopulator implements ServerDataProcessor {

    private CountDownLatch counter=new CountDownLatch(1);
    String[]  packages;

    public void getPagesFromServer() {
        new BackgroundDataPopulator(IMgrApplication.getAppContext().getString(R.string.list),new PData(),this).execute();

    }

    public String[] getPages() {
        try {

            counter.await();
        } catch (InterruptedException e) {
            packages=new String[0];
        }
        return packages;
    }

    @Override
    public void displayData(ServerOutput output) {


        Page[] pgArray = new Page[((PageData)output).getPages().size()];
        pages=new String[pgArray.length];
        pgArray = ((PageData)output).getPages().toArray(pgArray);
        for(int i=0;i<pgArray.length;i++){
            pages[i]=pgArray[i].getName();
        }
        counter.countDown();

    }

}





public class BackgroundDataPopulator extends AsyncTask<Void, String, ServerOutput> {
    // connector=new JSONConnector();
    Connector connector;
    String curUrl;
    ServerOutput curServerOutput;
    ServerDataProcessor processor;


    public BackgroundDataPopulator(String url, ServerOutput serverOutput,ServerDataProcessor curProcessor) {
        //connector = new UnitTestConnector();
        connector = new JSONConnector();
        curUrl = url;
        curServerOutput = serverOutput;
        processor=curProcessor;
    }

    @Override
    protected ServerOutput doInBackground(Void... params) {

        return connector.getData(URLUtils.getFormattedUrl(curUrl),curServerOutput);
    }

    @Override
    protected void onPostExecute(ServerOutput output) {
        processor.displayData(output);
        //Toast.makeText(BaseFragmentActivity.this, "Done!",Toast.LENGTH_SHORT).show();
    }
}




protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    pagePopulator=new PagePopulator();
    pagePopulator.getPagesFromServer();
    super.onCreate(savedInstanceState);

}

public ArrayAdapter<CharSequence> getSpinnerDataArray(String item) {
    return new ArrayAdapter<CharSequence>(this,android.R.layout.simple_spinner_item,pagePopulator.getPages());
}

Answer 1

It is not clear what exactly you are doing and where the AscynTask is being started. It looks like you are calling await() and countDown() on the same thread and that is why you are getting blocked. Post more details and/or debug your code.