1. API Level 13(3.2)미만

WindowManager windowManager = (WindowManager)getSystemService(Context.WINDOW_SERVICE);

Display display = windowManager.getDefaultDisplay();

display.getWidth();

display.getHeight();

2. API Level 13(3.2)이상

Point point = new Point();

display.getSize(point);

point.x;

point.y;

또는...

DisplayMetrics metrics = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(metrics);

metrics.widthPixels;

metrics.heightPixels;