(Android) How I get SmartPhone ScreenWidth and Height? [duplicate]

Question

I'm making game for Android and use SurfaceView.

I want to know SmartPhone Screen Info(Height, Width, ect..)

I uesd this code, but.. It is not correct value of display Width and Height,

It's always printed "0" by Red Color

What I miss?

public class MainActivity extends Activity {
private int width;
private int height;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    DisplayMetrics metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);
    width = metrics.widthPixels;
    height = metrics.heightPixels;

    setContentView(new GameView(this));
}

public class Painter extends Thread
public void run(){
    Canvas canvas = null;
    long start, end;
    int sleep;
     while(true) {
         if (runnable) {
             start = System.currentTimeMillis();

             try {
                 canvas = holder.lockCanvas(null);
                 paint.setColor(Color.RED);
                 paint.setTextSize(200);

                 synchronized (holder) {
                     canvas.drawText(Integer.toString(main.getHeight()), 600, 800, paint);
                     canvas.drawText(Integer.toString(main.getWidth()), 300, 400, paint);
                 }
             } catch (Exception e) {
                 e.printStackTrace();
             } finally {
                 holder.unlockCanvasAndPost(canvas);
             }

             end = System.currentTimeMillis();

             sleep = 1000 / FPS - (int) (end - start);
             try {
                 Thread.sleep(sleep > 0 ? sleep : 0);
             } // Try
             catch (InterruptedException e) {
                 e.printStackTrace();
             }
         }
     }

Answer 1

You can get it using this Code:

DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int height = displaymetrics.heightPixels;
int width = displaymetrics.widthPixels;

Works on all API versions, and therefore requires no API checking. If you are in a view, you might need to get the context:

((Activity) getContext()).getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);‌​