How do i make Android app which do something every X second

Question

Hello i wanna do apliacation which every 1 second call function or do something else. I have this code which is not working can you tell 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

You don't have a loop in run() function, try to change it like this:

    @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, it will run forever though. You should also use a handler to perform changes on UI from another thread, it can be done by example below:

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 2

It seems that you have two problems here.

1 - If you do not have a loop in your thread, the "showtime" method will be called just once.

2 - Modifying a UI component from a thread different to the main thread will fail.

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

Answer 3

I have alter the code by following

There are 3 ways all of them working(showing Log output).

But TextView isn't updating. 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 4

Like I said before, you got to modify your textView in the UI thread (the thread that created the component).

In order to do that use a Handler, like this : (Do not loop in your thread, just post 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 tick every 300 ms. You might see some strange seconds if you perform your "showtime" method every second.