Android ConstraintLayout getWidth return 0

Question

I use ConstraintLayout in my project. While I find a problem when I try to call getWidth in onCreate. The result is 0.

The code is here.

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_paint);
    iv = (ImageView) findViewById(R.id.iv);
    iv.setOnTouchListener(new ImageViewTouchListener());

    System.out.println("imageview width:" + iv.getWidth() + " height:" + iv.getHeight());
}

The layout design view

The xml content.

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btn_red"
        android:background="#ff0000"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btn_green"
        android:background="#00ff00"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toRightOf="@+id/btn_red" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btn_blue"
        app:layout_constraintLeft_toRightOf="@+id/btn_green"
        android:background="#0000ff"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintTop_toTopOf="parent" />

    <android.support.constraint.Guideline
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:id="@+id/guideline"
        android:orientation="horizontal"
        tools:layout_editor_absoluteY="55dp"
        tools:layout_editor_absoluteX="0dp"
        app:layout_constraintGuide_percent="0.09784412" />

    <SeekBar
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:id="@+id/sb_stroke"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        android:layout_marginTop="16dp"
        app:layout_constraintTop_toBottomOf="@+id/btn_green" />

    <android.support.constraint.Guideline
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/guideline4"
        android:orientation="horizontal"
        tools:layout_editor_absoluteY="103dp"
        tools:layout_editor_absoluteX="0dp"
        app:layout_constraintGuide_percent="0.1840796" />

    <ImageView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:id="@+id/iv"
        app:layout_constraintTop_toTopOf="@+id/guideline4"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        tools:ignore="ContentDescription"
        android:background="#22000000"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintVertical_bias="0.0" />

</android.support.constraint.ConstraintLayout>

I want to know how to get the right width and height of ImageView.

I try to get width and height in onStart and onResume but get the same result 0.

Possible duplicate of [getWidth() and getHeight() of View returns 0](http://stackoverflow.com/questions/3591784/getwidth-and-getheight-of-view-returns-0) — Mike M., Sep 23 '16 at 12:47
what was the question? the question and its answer could be important to someone else — nandsito, Oct 22 '16 at 07:36

score 7 · Answer 1 · answered Sep 23 '16 at 12:43

7

In OnCreate() your view has not yet been created as per your xml parameters. So you have to add addOnGlobalLayoutListener() on your view and you will get your dimensions in that listener once view has been created.

iv.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
    iv.getViewTreeObserver().removeGlobalOnLayoutListener(this);
    System.out.println("imageview width:" + iv.getWidth() + " height:" + iv.getHeight());
   }
});

answered Sep 23 '16 at 12:43

Nikhil

3,711
8
32
43

1

The method is useful. But this method was deprecated in API level 16. Use #removeOnGlobalLayoutListener instead – ittianyu Sep 23 '16 at 12:53
Will this work if width is set to match parent? – the_prole May 28 '20 at 16:44

score 6 · Accepted Answer · answered Sep 23 '16 at 12:38

6

Its because your view is not been created yet.

  iv.post(new Runnable() {
            @Override
            public void run() {
                 //height is ready
                 System.out.println("imageview width:" + iv.getWidth() + " height:" + iv.getHeight());
            }
        });

answered Sep 23 '16 at 12:38

Sohail Zahid

8,099
2
25
41

you are welcome:) – Sohail Zahid Sep 23 '16 at 12:55

Android ConstraintLayout getWidth return 0

2 Answers2