How to update a TextView in an activity constantly in an infinite loop?
10,110
Solution 1
use Handler and a separate thread/runnable for updating TextView constantly instead of While loop :
Handler handler=new Handler();
handler.post(new Runnable(){
@Override
public void run() {
// upadte textView here
handler.postDelayed(this,500); // set time here to refresh textView
}
});
Solution 2
Minimal working example
Based on https://stackoverflow.com/a/14295193/895245:
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;
public class Main extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final int i = 0;
final TextView textView = new TextView(this);
textView.setText(String.format("%d", i));
setContentView(textView);
final Handler handler = new Handler();
class MyRunnable implements Runnable {
private Handler handler;
private int i;
private TextView textView;
public MyRunnable(Handler handler, int i, TextView textView) {
this.handler = handler;
this.i = i;
this.textView = textView;
}
@Override
public void run() {
this.handler.postDelayed(this, 500);
this.i++;
this.textView.setText(String.format("%d", i));
}
}
handler.post(new MyRunnable(handler, i, textView));
}
}
You can just copy paste this into the main activity generated by android create project [...]
, and you will see a counter on your app.
Tested on Android 22.
Comments
-
aclowkay almost 2 years
I have an activity which has a TextView, and I want to update the text constantly..
In Java I could just make an infinite while loop, and just set the text each iteration.
But when I try to do that in Android, it shows a black screen, and doesn't even load the activity.
I put the infinite in the
onCreate
method, perhaps that's why it crashes..but if it is, where should I put it? -
MattD about 10 yearsIf you are going to refer to handler as part of that closure, you need to delcare it final.