14_自定义View重绘

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.view.Menu;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(new RenderView(this));
    }
}

class RenderView extends View {
    Random rand = new Random();

    public RenderView(Context context) {
        super(context);
    }

    protected void onDraw(Canvas canvas) {
        canvas.drawRGB(rand.nextInt(256), rand.nextInt(256),
                rand.nextInt(256));
        invalidate();
    }
}