Why does LinearLayout child getWidth method return 0?

Question

I have a LinearLayout, and this LinearLayout will hold dynamically placed views. I need to find out what the width of the children of LinearLayout, however this has to be do

Answer 1

inside the onCreate , views still can't know the state of the nearby views and the children ,etc... so only after all is prepared and the layout process is done , you can get the size of views .

here's a quick code for getting the size of the view just before it's being drawn:

private static void runJustBeforeBeingDrawn(final View view, final Runnable runnable)
{
    final ViewTreeObserver vto = view.getViewTreeObserver();
    final OnPreDrawListener preDrawListener = new OnPreDrawListener()
    {
        @Override
        public boolean onPreDraw()
        {
            Log.d(App.APPLICATION_TAG, CLASS_TAG + "onpredraw");
            runnable.run();
            final ViewTreeObserver vto = view.getViewTreeObserver();
            vto.removeOnPreDrawListener(this);
            return true;
        }
    };
    vto.addOnPreDrawListener(preDrawListener);
}

alternatively , you can use addOnGlobalLayoutListener instead of addOnPreDrawListener if you wish.

example of usage :

runJustBeforeBeingDrawn(view,new Runnable()
{
  @Override
  public void run()
  {
    int width=view.getWidth();
    int height=view.getHeight();
  }
});

another approach is to use onWindowFocusChanged (and check that hasFocus==true) , but that's not always the best way ( only use for simple views-creation, not for dynamic creations)

EDIT: Alternative to runJustBeforeBeingDrawn: https://stackoverflow.com/a/28136027/878126