Custom AlertDialog - problem with android.R.id.custom

Question

I'm sure I'm missing the point here so I'm hoping someone can explain.

I want to create a popup when a user touches an ImageView. I had a look at AlertDialog and the docs say...

If you want to display a more complex view, look up the FrameLayout called "custom" and add your view to it:

...with the following code...

    FrameLayout fl = (FrameLayout) findViewById(android.R.id.custom);
    fl.addView(myView, new LayoutParams(MATCH_PARENT, WRAP_CONTENT));

So as a test I tried the following in my onCLick() method...

    TextView tv = new TextView(this);
    tv.setText("Hello World");
    FrameLayout customFrameLayout = (FrameLayout) findViewById(android.R.id.custom);
    customFrameLayout.addView(tv, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));

The last line of the above where I'm calling addView throws a NullPointerException which makes me think there's a problem with android.R.id.custom.

So the question is, what is wrong with the above and also is there a better way of creating a custom popup (perhaps by using the Dialog class or extending it)?

NOTE: I'm only using TextView in this example as a test, I want to add something more complex for my actual popup.

Answer 1

One option is to create an Activity and style it using the dialog theme:

<activity android:theme="@android:style/Theme.Dialog">

See applying themes for more information.