getLocationOnScreen crashes

I need to get the coordinates of my app on screen to use them as an of开发者_如何学编程fset for a popout.

                    View tempView = (View) findViewById(R.layout.main);
                    int[] loc = {0,0};
                    tempView.getLocationOnScreen(loc); /// crashes here!

Tried this code, but the last line of it makes the app crash. Maybe the tempView I'm getting from the main layout somehow doesn't correspond with the layout on screen?

Any suggestions... thanks! :)

added: solved

                    int[] loc = new int[2]; 
                    View tempView = (View) findViewById(R.id.LL_whole);
                    tempView.getLocationOnScreen(loc);

                    post( String.valueOf(loc[1]) );

works! :)

Try checking to see if tempView is null. I suspect findViewById() is failing to find the id you've given it.

int[] loc = {0,0};
View tempView = (View) findViewById(R.layout.main);
if (tempView != null) {
    tempView.getLocationOnScreen(loc);
} else {
    Log.d("YourComponent", "tempView was null.");
}

In your XML you have something like this:

<SomeLayout android:id="@+id/myLayout" ... >

    <SomeView android:id="@+id/myView" ... />
    <SomeOtherView android:id="@+id/myOtherView" .../>

</SomeLayout>

So you want to say:

SomeView v = (SomeView)findViewById(R.id.myView);  

Or perhaps:

SomeLayout l = (SomeLayout)findViewById(R.id.myLayout);

findViewById(R.layout.main)

You should place here R.id.something not R.layout.something.