How to use textview.getLayout()? It returns null

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孤独总比滥情好 2020-12-01 10:50

I’m trying set a layout for textview so I can use getEllipsisCount() method. But below code returns null as layout value. How can I take layout and

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  • 2020-12-01 11:28

    From the documentation:

    public final Layout getLayout ()

    Added in API level 1 Returns the Layout that is currently being used to display the text. This can be null if the text or width has recently changes.

    So probably your text has changes or you call it too early.

    Look at this answer where is stated

    This only works after the layout phase, otherwise the returned layout will be null, so call this at an appropriate place in your code.

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  • 2020-12-01 11:30

    First, I do not know if it is a typo or it is intentional but you have declared a "settext" method instead of the predefined setText. However to get a reference of your layout I suggest you the following:

    LayoutInflater inflater = getLayoutInflater();
    
    RelativeLayout textViewLayout = (RelativeLayout) inflater.inflate(R.layout.activity_main,null);
    
    if (textViewLayout != null) {
        mytextview.setText("very good layout worked\n");
    }
    

    supposing that your TextView belongs to a RelativeLayout.

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  • 2020-12-01 11:44

    I recently encountered this problem myself. For any newcomers to this thread, the accepted answer by @Pragnani along with the comment from @dimsuz provides a nice and compact solution. Adding an OnPreDrawListener to the view tree of the text view, wait for a reference to a layout and use it, and lastly remove the listener after any work requiring the layout is finished.

    Given the example code from OP, implementing the solution could look something like this:

    public class MainActivity extends Activity implements ViewTreeObserver.OnPreDrawListener {
    
        // maintain a reference to the view so we can later remove the listener
        private TextView mytextview;
    
        @Override
        public boolean onPreDraw() {
            Layout layout = mytextview.getLayout();
            if (layout != null) {
    
                // use layout here...
                int n = layout.getEllipsisCount(0);
    
                // work requiring a layout is finished; remove listener from view
                mytextview.getViewTreeObserver().removeOnPreDrawListener(this);
            }
            return true;
        }
    
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            mytextview = (TextView) findViewById(R.id.textView1);
    
            // add listener to the view
            mytextView.getViewTreeObserver().addOnPreDrawListener(this);
        }
    }
    
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  • 2020-12-01 11:46

    Call

    TextView.onPreDraw();
    

    It creates the layout.

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  • 2020-12-01 11:47

    Call mytextview.getLayout() in onStart or onResume callback.

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  • 2020-12-01 11:50

    You are calling it too early, thats why it is returning null

    Try this

      ViewTreeObserver vto = mytextview.getViewTreeObserver();
        vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
               Layout layout = mytextview.getLayout();  
            }
        });
    
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