Android视图更新示例-优快云博客

本文链接：https://blog.youkuaiyun.com/radishkill/article/details/54863829

本文展示了一个简单的Android应用程序示例，通过不断的更新视图位置来模拟运动效果。该程序利用Handler和Runnable实现循环更新UI，并使用Canvas绘制圆形。

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public class MainActivity extends AppCompatActivity {
    View v=null;
    int Width,Height;
    int x,y;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Width=getWindowManager().getDefaultDisplay().getWidth();//得到宽
        Height=getWindowManager().getDefaultDisplay().getHeight();//得到高
        x=Width/10;
        y=Height/10;
        setContentView(R.layout.activity_main);
        v=findViewById(R.id.activity_main);
        handler.post(runnable);
    }
    Handler handler =new Handler(){
        @Override
        public void handleMessage(Message msg) {
            setContentView(new MyView(MainActivity.this));
            handler.post(runnable);
            super.handleMessage(msg);
        }
    };
    Runnable runnable=new Runnable() {
        int i=2;
        @Override
        public void run() {
            y+=1;
            i+=10;
            Message msg=handler.obtainMessage();
            try {
                Thread.sleep(24);
            }
            catch (InterruptedException ex)
            {
                ex.printStackTrace();
            }
            handler.sendMessage(msg);
            if(y==Height)
            {
                handler.removeCallbacks(runnable);
            }
        }
    };
    class MyView extends View
    {
        public  MyView(Context context)
        {
            super(context);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            Paint paint=new Paint();
            paint.setColor(Color.BLACK);
            canvas.drawCircle(x,y,30,paint);
            super.onDraw(canvas);
        }
    }