how to set width which is equal to another widget on android

Question

I need to draw a horizontal line below a text field such that the width of the line equals the text width (not the width of the full screen).

In my app I have a textview

Answer 1

What Jave said is correct - and the easiest, but what if you're not using a RelativeLayout to contain the View's ?

If you're customizing your UI within onCreate() then you'll find that obtaining the width from another widget will give you an incorrect result ! That's because the UI hasn't been set up yet.

But you can still set up your UI within onCreate... simply run code that executes after the UI is set up. This is achieved through use of the View.post() command.

The XML :

Java code:

private Button mButtonOne;
private Button mButtonTwo;

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);

    // inflate UI
    setContentView(R.layout.activity_example);

    // get references to UI elements
    mButtonOne = (Button)findViewById(R.id.button_one);
    mButtonTwo = (Button)findViewById(R.id.button_two);

    // Make buttons the same size (i.e. Button1.width = Button2.width)
    if ((mButtonOne != null) && (mButtonTwo != null))
    {
        mButtonOne.post(new Runnable()
        {
            @Override
            public void run()
            {
                mButtonOne.setWidth(mButtonTwo.getWidth());
            }
        });
    }
}

The result is that the Width of button_one will match the Width of button_two. This is a nicer look when the amount of text varies heavily between the two View's.