1.在activity中獲取

public class TActivity extends AppCompatActivity{
  @Override
public void onCreate(
      @Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState)
  {
     super.onCreate(savedInstanceState, persistentState);
     WindowManager manager = getWindowManager();
     DisplayMetrics metrics = new 
 
DisplayMetrics();
     manager.getDefaultDisplay().getMetrics(metrics);
     int width = metrics.widthPixels;  //以要素為單位
int height = metrics.heightPixels;
  }
}

public class text {
  public text(Context context) {
     -------------------------1111111-------------------

     WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE
 
);
     int width = manager.getDefaultDisplay().getWidth();
     int height = manager.getDefaultDisplay().getHeight();
     

     -------------------------2222222-----------------------

     DisplayMetrics metrics = new DisplayMetrics();
     manager.getDefaultDisplay().getMetrics(metrics);
     int 
 
width2 = metrics.widthPixels;  //以要素為單位
int height2 = metrics.heightPixels;

     ---------------------------33333-------------------
     Point point = new Point();
     manager.getDefaultDisplay().getSize(point);
     int width3 = point.x;  //沒去驗證,有需要的可以打個log看下.
     int height3 = point.y;
  }
}