I tried to use following code to get screen width and height in android app development:
Display display = getWindowManager().getDefaultDisplay();
int screenWidth = display.getWidth();
int screenHeight = display.getHeight();
but I got NullPointerException for my display
, why? how to get screen width and height then?
If you're calling this outside of an Activity, you'll need to pass the context in (or get it through some other call). Then use that to get your display metrics:
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
int width = metrics.widthPixels;
int height = metrics.heightPixels;
UPDATE: With API level 17+, you can use getRealSize
:
Point displaySize = new Point();
activity.getWindowManager().getDefaultDisplay().getRealSize(displaySize);
If you want the available window size, you can use getDecorView
to calculate the available area by subtracting the decor view size from the real display size:
Point displaySize = new Point();
activity.getWindowManager().getDefaultDisplay().getRealSize(displaySize);
Rect windowSize = new Rect();
ctivity.getWindow().getDecorView().getWindowVisibleDisplayFrame(windowSize);
int width = displaySize.x - Math.abs(windowSize.width());
int height = displaySize.y - Math.abs(windowSize.height());
return new Point(width, height);
getRealMetrics
may also work (requires API level 17+), but I haven't tried it yet:
DisplayMetrics metrics = new DisplayMetrics();
activity.GetWindowManager().getDefaultDisplay().getRealMetrics(metrics);