How to limit the height of Spinner drop down view in Android

You can also affect drop down view location and size by subclassing Spinner and overriding its getWindowVisibleDisplayFrame(Rect outRect) which is used by android.widget.PopupWindow for calculations. Just set outRect to limit the area where drop down view can be displayed.

This approach is of course not suitable for all scenarios since sometimes you want to place drop down view so it doesn't obscure another view or by some other condition known only "outside the instance".

In my case, I needed to apply FLAG_LAYOUT_NO_LIMITS flag to my activity window which caused the outRect to be huge and therefore part of the drop down view got sometimes hidden behind navigation bar. In order to restore original behavior I used the following override:

@Override
public void getWindowVisibleDisplayFrame(Rect outRect) {
    WindowManager wm = (WindowManager) getContext.getSystemService(Context.WINDOW_SERVICE);
    Display d = wm.getDefaultDisplay();
    d.getRectSize(outRect);
    outRect.set(outRect.left, <STATUS BAR HEIGHT>, outRect.right, outRect.bottom);
}

As of year 2021 I would go with: Exposed Dropdown Menus and use inside AutoCompleteTextView the following:

android:dropDownHeight="300dp"

If you don't know what is this all about start exploring: Menu-Display & Menu-Documentation

You can use Reflection.

    Spinner spinner = (Spinner) findViewById(R.id.spinner);
    try {
        Field popup = Spinner.class.getDeclaredField("mPopup");
        popup.setAccessible(true);

        // Get private mPopup member variable and try cast to ListPopupWindow
        android.widget.ListPopupWindow popupWindow = (android.widget.ListPopupWindow) popup.get(spinner);

        // Set popupWindow height to 500px
        popupWindow.setHeight(500);
    }
    catch (NoClassDefFoundError | ClassCastException | NoSuchFieldException | IllegalAccessException e) {
        // silently fail...
    }