自己绘制的三角形通过按键事件左右移动，各位大神看看我的问题怎么解决！！

我的图形不能动，求大神们指出我的问题
下面是我的代码：
public class MainActivity extends Activity {
    MyView myView = null;

    Runnable runnable=new Runnable() {
        
        @Override
        public void run() {
            myView.move();
            
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myView = new MyView(this) ;
        setContentView(myView);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}
绘图的类：
public class MyView extends View{
    private Paint paint;
    int x = 160;
    int y = 160;
    public MyView(Context context) {
        super(context);

        paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(Color.RED);
        paint.setStyle(Paint.Style.FILL);
    }

    @Override
    public void draw(Canvas canvas) {

        Path path = new Path();
        path.moveTo(x, y);
        path.lineTo(x - 60, y + 80);
        path.lineTo(x + 60, y + 80);
        path.close();
        canvas.drawPath(path, paint);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
            if (x > 0) {
                x -= 4;
            }
        } else if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) {
            if (x < 319) {
                x += 4;
            }
        }

        return true;
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event) {
        // TODO Auto-generated method stub
        return true;
    }

    public void move() {
        this.invalidate();
    }

}