Set font for all textViews in activity?

Solution1:: Just call these method by passing parent view as argument.

private void overrideFonts(final Context context, final View v) {
    try {
        if (v instanceof ViewGroup) {
            ViewGroup vg = (ViewGroup) v;
            for (int i = 0; i < vg.getChildCount(); i++) {
                View child = vg.getChildAt(i);
                overrideFonts(context, child);
         }
        } else if (v instanceof TextView ) {
            ((TextView) v).setTypeface(Typeface.createFromAsset(context.getAssets(), "font.ttf"));
        }
    } catch (Exception e) {
 }
 }

Solution2:: you can subclass the TextView class with your custom font and use it instead of textview.

public class MyTextView extends TextView {

    public MyTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    public MyTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public MyTextView(Context context) {
        super(context);
        init();
    }

    private void init() {
        if (!isInEditMode()) {
            Typeface tf = Typeface.createFromAsset(getContext().getAssets(), "font.ttf");
            setTypeface(tf);
        }
    }

}