How to make an Android app that does something every X seconds

Question

Hi, I want to make an application that calls a function or something else every 1 second. I have this code that does not work, can you say what is wrong?

public class App5_Thread extends Activity implements Runnable { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Thread thread = new Thread(this); thread.start(); } @Override public void run() { TextView tv1 = (TextView) findViewById(R.id.tv); showTime(tv1); try { Thread.sleep(1000); }catch (Exception e) { tv1.setText(e.toString()); } } public void showTime(TextView tv1 ){ String DATE_FORMAT_NOW = "yyyy-MM-dd HH:mm:ss"; Calendar cal = Calendar.getInstance(); SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW); tv1.setText(sdf.format(cal.getTime())+" "+System.currentTimeMillis()); } 

}

Answer 1

I changed the code following

There are 3 ways to work all (showing Log output).

But TextView is not updated. Why?

 package cz.cvut.fel.android; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Timer; import java.util.TimerTask; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.widget.TextView; public class App5_RepeatedAction extends Activity { static TextView tv1; static class MyThread implements Runnable { public void run() { boolean end = false; while (!end) { String txt = "Vlakno id:" + Thread.currentThread().getId()+" THREAD"; Log.v("MyActivity", txt); //tv1.setText(txt); showTime(tv1); try { Thread.sleep(10000); } catch (InterruptedException ex) { System.err.println(ex.toString()); } } } } static void showTime(TextView tv1 ){ String DATE_FORMAT_NOW = "yyyy-MM-dd HH:mm:ss"; Calendar cal = Calendar.getInstance(); SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW); tv1.setText(sdf.format(cal.getTime())+" "+System.currentTimeMillis()); } /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); tv1 = (TextView) findViewById(R.id.tv); //----------ScheduledExecutorService ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor(); exec.scheduleAtFixedRate(new Runnable() { @Override public void run() { String txt = "ScheduledExecutorService"; Log.v("MyActivity", txt); //tv1.setText(txt); showTime(tv1); } }, 0, 5, TimeUnit.SECONDS); //----------TIMER Timer timer = new Timer(); timer.scheduleAtFixedRate(new TimerTask() { @Override public void run() { String txt = "Timer"; Log.v("MyActivity", txt); //tv1.setText(txt); showTime(tv1); } }, 0, 1000); //-----------THREAD try { boolean quit = false; Thread t = new Thread(new MyThread()); //t.setDaemon(true); t.start(); } catch (Exception e) { System.err.println(e.toString()); } } } 

Answer 2

You do not have a loop function in the run () function, try changing it as follows:

  @Override public void run() { TextView tv1 = (TextView) findViewById(R.id.tv); while(true){ showTime(tv1); try { Thread.sleep(1000); }catch (Exception e) { tv1.setText(e.toString()); } } } 

Be careful, this will go on forever. You should also use a handler to make changes to the user interface from another thread, this can be done using the following example:

 Handler mHandler = new Handler(); @Override public void run() { final TextView tv1 = (TextView) findViewById(R.id.tv); while(true){ try { mHandler.post(new Runnable(){ @Override public void run() { showTime(tv1); } ); Thread.sleep(1000); }catch (Exception e) { //tv1.setText(e.toString()); } } } 

Answer 3

As I said, you need to change your textView in the user interface thread (the thread that created the component).

To do this, use a handler, for example: (Do not loop in your thread, just send a message to the handler)

 private TextView tv1; Handler tick_Handler = new Handler(); MyThread tick_thread = new MyThread(); private class MyThread implements Runnable { public void run() { String txt = "Vlakno id:" + Thread.currentThread().getId()+" THREAD"; Log.v("MyActivity", txt); //tv1.setText(txt); showTime(tv1); tick_Handler.postDelayed(tick_thread, 1000); } } String DATE_FORMAT_NOW = "yyyy-MM-dd HH:mm:ss"; SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW); private void showTime(TextView tv ){ Calendar cal = Calendar.getInstance(); tv.setText(sdf.format(cal.getTime())+" "+System.currentTimeMillis()); } /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); tv1 = (TextView) findViewById(R.id.tv); tick_Handler.post(tick_thread); } 

By the way, if you want to have an accurate timer, you should indicate every 300 ms. You may see some strange seconds if you execute your "showtime" method every second.

Answer 4

You seem to have two problems.

1 - If there is no loop in your thread, the showtime method will be called only once.

2 - Changing the user interface component from a thread other than the main thread will not be performed.

You should find what you want here: http://developer.android.com/resources/articles/timed-ui-updates.html