Android: simple time counter

Question

I have a simple program with one TextView and two Buttons: Button1 and Button2.

Clicking on Button 1 will start a counter, increasing by 1 every 1 second and show result on TextView; clinking on Button 2 will stop it. Here is a part of my code for Button1. But it does not work.

    Timer T=new Timer();
    T.scheduleAtFixedRate(new TimerTask() {         
            @Override
            public void run() {
                myTextView.setText("count="+count);
                count++;                
            }
        }, 1000, 1000);

I know that there are some similar questions about this using Thread but it seems like they do not mention about stopping the counter.

Any suggestion is really appreciated.

Added:

Hello, I just shortened my code just to this from a much bigger program, but it is still crashed:

package com.example.hello;
import java.util.Timer;
import java.util.TimerTask;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;
public class MainActivity extends Activity {
    TextView myTextView;
    int count=0;
    Timer T;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myTextView=(TextView)findViewById(R.id.t);
        T=new Timer();
        T.scheduleAtFixedRate(new TimerTask() {         
            @Override
            public void run() {
                myTextView.setText("count="+count);
                count++;                
            }
        }, 1000, 1000);       
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    
}

The log file (I do not want to post this because it is too long but someone requested it):

07-28 17:35:07.012: W/dalvikvm(11331): threadid=7: thread exiting with uncaught exception (group=0x4001d800)
07-28 17:35:07.016: E/AndroidRuntime(11331): FATAL EXCEPTION: Timer-0
07-28 17:35:07.016: E/AndroidRuntime(11331): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.view.ViewRoot.checkThread(ViewRoot.java:2802)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.view.ViewRoot.requestLayout(ViewRoot.java:594)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.view.View.requestLayout(View.java:8125)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.view.View.requestLayout(View.java:8125)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.view.View.requestLayout(View.java:8125)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.view.View.requestLayout(View.java:8125)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:254)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.view.View.requestLayout(View.java:8125)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.widget.TextView.checkForRelayout(TextView.java:5378)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.widget.TextView.setText(TextView.java:2688)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.widget.TextView.setText(TextView.java:2556)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at android.widget.TextView.setText(TextView.java:2531)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at com.example.hello.MainActivity$1.run(MainActivity.java:21)
07-28 17:35:07.016: E/AndroidRuntime(11331):    at java.util.Timer$TimerImpl.run(Timer.java:289)

user_4469965 · Answer

Perfect solution if you want to display running clock.

private void startClock(){
    Thread t = new Thread() {

        @Override
        public void run() {
            try {
                while (!isInterrupted()) {
                    Thread.sleep(1000);
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Calendar c = Calendar.getInstance();

                            int hours = c.get(Calendar.HOUR_OF_DAY);
                            int minutes = c.get(Calendar.MINUTE);
                            int seconds = c.get(Calendar.SECOND);

                            String curTime = String.format("%02d  %02d  %02d", hours, minutes, seconds);
                            clock.setText(curTime); //change clock to your textview
                        }
                    });
                }
            } catch (InterruptedException e) {
            }
        }
    };

    t.start();
}

user_8468699 · Answer

This way it is much simpler. It is a feature made available on the android developer site. Link

public void initCountDownTimer(int time) {
    new CountDownTimer(30000, 1000) {

        public void onTick(long millisUntilFinished) {
            textView.setText("seconds remaining: " + millisUntilFinished / 1000);
        }

        public void onFinish() {
            textView.setText("done!");
        }
    }.start();
}

Kotlin Version

fun initCountDownTimer(time: Int) {
object : CountDownTimer(30000, 1000) {
    override fun onTick(millisUntilFinished: Long) {
        textView.setText("seconds remaining: " + millisUntilFinished / 1000)
    }

    override fun onFinish() {
        textView.setText("done!")
    }
}.start()

}

user_4464562 · Answer

As @hovanessyan suggested: You can use the Chronometer class. E.g., as follows (with Kotlin, Java analog):

class ChronometerToggler: Fragment() {
    private lateinit var chronometer: Chronometer
    private var isChronometerRunning = false
    private lateinit var toggleButton: FloatingActionButton

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        val view = inflater.inflate(R.layout.my_layout, container, false)
        chronometer = view.findViewById(R.id.chronometer)
        toggleButton = view.findViewById(R.id.toggle_button)
        toggleButton.setOnClickListener {
            onToggleButtonPressed()
        }
        return view
    }

    private fun onToggleButtonPressed() {
        isChronometerRunning = !isChronometerRunning
        if (isChronometerRunning) {
            chronometer.base = SystemClock.elapsedRealtime()
            chronometer.start()
        }
        else {
            chronometer.stop()
        }
    }
}

In the my_layout.xml:

[...]
     
[...]

Android: simple time counter

6 Answers