How to set text of text view in another thread

Question

I am tring to setText in another thread, that is, child thread. But for the following code, it is giving the error

Only the original thread that created a view hierarchy can touch its views.

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    img = (ImageView)findViewById(R.id.img);
    pb = (ProgressBar)findViewById(R.id.pb);
    this.tv = (TextView)findViewById(R.id.perc);
    tv.setText("30 %");
    pb.setProgress(30);
    pb.setMax(100);
}

public void set(int p)
{
    tv.setText(p + " %");
}

protected void onStart()
{
    super.onStart();
    pb.setProgress(20);

    Thread t = new Thread(new Runnable()
    {
        @Override
        public void run()
        {
            try {
                int i = pb.getProgress();
                while(i <100)
                {
                    while(pb.getProgress()<100)
                    {
                        pb.incrementProgressBy(5);
                        Thread.sleep(1000);
                    }
                i+=10;
                pb.setProgress(i);
                Thread.interrupted();
                set(i);
                }
            }
            catch (InterruptedException e)
            {
                e.printStackTrace();
            }
        }
    });
    t.start();
}

Ravi,u can't directly update UI from thread use `Handlers` and `AsyncTask` and see this [Android Threads, Handlers and AsyncTask ](http://www.vogella.de/articles/AndroidPerformance/article.html) — ρяσѕρєя K, Mar 27 '12 at 06:21
U mean a different Thread to set Text which will use handler.post(new Runnable(){ // }); — Ravi Ranjan, Mar 27 '12 at 06:24
you trying to set `TextView` value in Thread that's why u are getting this error — ρяσѕρєя K, Mar 27 '12 at 06:27

score 62 · Accepted Answer · edited Feb 28 '22 at 12:43

62

You need a reference to that textview and then do:

textView.post(new Runnable() {
    public void run() {
        textView.setText(yourText);
    } 
});

in Kotlin:

val textView: TextView = findViewById(R.id.textView)
textView.post(Runnable { textView.setText(yourText) })

edited Feb 28 '22 at 12:43

nacho1111

73
1
8

answered Mar 27 '12 at 06:24

Bondax

3,143
28
35

Thanks this worked. I just want to know that this is creating new child thread of working in UI(parent thread). – Ravi Ranjan Mar 27 '12 at 06:42
@LoungeKatt There is only one UI-Thread. `View.post` uses the Handler, while `Context.runOnUiThread` checks, if the calling thread is the ui thread and posts to Handler, otherwise. – Bondax Mar 26 '18 at 07:54
@LoungeKatt I had to giggle when I read that you think taking "separate UI thread" as something different than "separate reference" is "taking it too literally" – Bondax Mar 27 '18 at 08:09
@Bondax Glad something made you laugh. It sounds like you take yourself entirely too seriously. If you need the whole thing explained using appropriate wording and clear examples, you should probably start a separate question. – Abandoned Cart Mar 27 '18 at 08:42
https://stackoverflow.com/a/10558238/461982 To avoid confusion for later viewers: the key difference is that `runOnUiThread` may still cause an `android.view.ViewRoot$CalledFromWrongThreadException` while `post` will maintain the specific reference to the view being edited. Hopefully this wording is clear enough for you ;) – Abandoned Cart Mar 27 '18 at 08:48
Tbis answer helped a lot I was getting lines of text in runnable, for read more /read less. Works fine in latest devices, but gave textview must not null on 21 api. I AM DOING textview.Layout.Getlines – MRamzan Dec 25 '20 at 06:40

score 11 · Answer 2 · edited Sep 16 '12 at 19:25

11

Use runOnUiThread for updating the UI control. In your case:

runningActivity.runOnUiThread(new Runnable() {
    public void run() {
        tv.setText(p + " %");
    }
});

Edited:

Activity mActivity;
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    mActivity= this;
   ...
   ..//The rest of the code
} //close oncreate()

thread{
    mActivity.runOnUiThread(new Runnable() {
        public void run() {
            tv.setText(p + " %");
        }
    });
}

edited Sep 16 '12 at 19:25

Peter Mortensen

30,738
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answered Mar 27 '12 at 06:23

Mohammed Azharuddin Shaikh

41,633
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115

How to initialized Activity runningActivity. Initializing it with null is giving run time error. – Ravi Ranjan Mar 27 '12 at 06:36
Thanks . This worked , Kindly suggest me which two use because both are working. 1) runningActivity.runOnUiThread or 2) textView.post – Ravi Ranjan Mar 27 '12 at 06:58
refer http://stackoverflow.com/questions/3652560/what-is-the-android-uithread-ui-thread – Mohammed Azharuddin Shaikh Mar 27 '12 at 07:04

bigspawn · Answer 3 · 2015-04-05T18:21:45.330

2

You can use handle :

handler.post(new Runnable() {
    public void run() {
        textView.setText(yourText);
    }
});

But your textView and yourText must be class fields.

In your thread (activity) where you create textView use:

Handler handler = new Handler();

And pass handler into another thread.

edited Apr 05 '15 at 18:21

answered Apr 05 '15 at 18:16

bigspawn

1,727
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score 2 · Answer 4 · edited Mar 27 '12 at 06:30

2

Either you can use runOnUiThread or use Handler to set text in TextView.

edited Mar 27 '12 at 06:30

Mohammed Azharuddin Shaikh

41,633
14
96
115

answered Mar 27 '12 at 06:26

Richa

3,165
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26

How to set text of text view in another thread

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