Question

the Android devGuide explains how it is possible to reference the value of an attribute in the currently-applied theme, using the question-mark (?) instead of at (@).

Does anyone know how to do this from code, e.g. in a customized component?

Answer 1

In XML, it would look something like this:

style="?header_background"

programmatically, it’s a little trickier. In your activity:

private static Theme theme = null;

protected void onCreate(Bundle savedInstanceState) {
   ...
   theme = getTheme();
   ...
}

public static int getThemeColors(int attr){
   TypedValue typedvalueattr = new TypedValue();
   theme.resolveAttribute(attr, typedvalueattr, true);
   return typedvalueattr.resourceId;
}

And when you want to access an attribute of the theme, you would do something like this:

int outside_background = MyActivity.getThemeColors(R.attr.outside_background);
setBackgroundColor(getResources().getColor(outside_background));

It’s a little more convoluted, but there you go 😉