Update Progressbar in the background java android

Question

How do I update the background service ProgressBar in the Android?

My code:

public void onClick(View v) {
    // inicial o progressbar
            progressBar = new ProgressDialog(v.getContext());
            progressBar.setCancelable(true);
            progressBar.setMessage("Exportando os dados...");
            progressBar.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            progressBar.setProgress(0);
            progressBar.setMax(100);
            progressBar.show();

// Inicia o serviço a partir de INICIAR_SERVICO definido no

    startService(new Intent("INICIAR_SERVICO"));

I don’t know how to use the progressBar.setProgress(); in the class of the service called.

Answer 1

The service can’t call progressBar.setProgress() directly. He needs to find a way to ask Activity visible at that time when this method is called.

I see two possibilities: the first, which is not my favorite because it is a little more complicated, is to engage (bind) to the service and thus allow the service to communicate with the Activity in question. In order to do this, reference should be made to a listener that the service goes calling every time progress should be increased. In Activity, the listener executes progressBar.setProgress(). The documentation explains how to do connect to a service.

The second, which I prefer, is to transmit updates from progress via broadcast. You record a BroadcastReceiver associated with the life cycle of its Activity (for example, is made the registerReceiver() in onResume() and the unregisterReceiver() in onPause() - a question of mine here, I’m not sure if the best methods for this are the pair onResume()/onPause() or onStart()/onStop()). And when the Activity gets a broadcast intent containing the new value of progress, flame progressBar.setProgress().

Code you can rely on:

Minhaactivity.java:

public class MinhaActivity extends Activity {

    private BroadcastReceiver mReceiver;
    private IntentFilter mFilter;

protected void onCreate(Bundle savedInstanceState) {
    mFilter = new IntentFilter();
    mFilter.addAction("ATUALIZA_PROGRESSO");
    mReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if ("ATUALIZA_PROGRESSO".equals(intent.getAction())) {
                mProgressBar.setProgress(intent.getIntExtra("progress"));
                if (intent.getIntExtra("progress") >= 100) {
                    mProgressBar.dismiss();
                }
            }
        }
    }

    mProgressBar = new ProgressDialog(v.getContext());
    mProgressBar.setCancelable(true);
    mProgressBar.setMessage("Exportando os dados...");
    mProgressBar.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    mProgressBar.setProgress(0);
    mProgressBar.setMax(100);
}

public void onClick(View v) {
    // inicia o progressbar
    mProgressBar.show();

    // Inicia o serviço
    startService(new Intent(this, MeuServico.class));
}

protected void onResume() {
    registerReceiver(mReceiver, mFilter);
}

protected void onPause() {
    unregisterReceiver(mReceiver);
}

Meuservice.java

public class MeuService extends IntentService {
    protected void onHandleIntent(Intent intent) {
        while (tarefaNaoTerminada) {
            (...)
            Intent intentAEnviar = new Intent("ATUALIZA_PROGRESSO");
            intentAEnviar.putExtra("progress", progresso);
            sendBroadcast(intentAEnviar);
        }
    }
}