Android：一个 Activity 的多个视图

Question

这是我的主要内容：

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    LinearLayout layout = (LinearLayout) findViewById(R.id.mainView);
    TextView text=  (TextView) findViewById(R.id.text);
    text.setText("This is a Test!");

    firstCircle first = new firstCircle(this);
    secondCircle second = new secondCircle(this);
    layout.addView(first);
    layout.addView(second);

}

这是我的firstCircleClass：

public class firstCircle extends SurfaceView implements SurfaceHolder.Callback {

private firstThread _firstThread;
private secondThread _secondThread;
private SurfaceHolder surfaceHolder;


public firstCircle (Context context, AttributeSet attrs){
    super(context,attrs);
    getHolder().addCallback(this);
    setFocusable(true);
    _firstThread= new firstThread(getHolder(),this);

}

public firstCircle (Context context){
    super(context);
    getHolder().addCallback(this);
    setFocusable(true);
    _firstThread= new firstThread(getHolder(),this);

}

@Override
public void onDraw(Canvas c){

    String tag="My Activity";
    Paint paint = new Paint();
    paint.setColor(Color.BLUE);

      c.drawCircle(100,100,100,paint);

}

@Override
public void surfaceCreated(SurfaceHolder holder){
    _firstThread.setRunning(true);
    _firstThread.start();
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height){

}

@Override
public void surfaceDestroyed(SurfaceHolder holder){
    boolean retry = true;
    _firstThread.setRunning(false);
    while (retry){
        try{
            _firstThread.join();
            retry = false;
        }catch (InterruptedException e){
            e.printStackTrace();
        }
    }
}




}

我有一个secondCircle类，它与上面的名称完全相同，并且圆圈的颜色为红色。

这是我的firstThread 类：

public class firstThread extends Thread {

private SurfaceHolder _surfaceHolder;
private firstClass _firstClass;
private boolean _run = false;

public firstThread (SurfaceHolder surfaceHolder, firstClass first){
    _surfaceHolder = surfaceHolder;
    _firstClass= first;

}


public void setRunning (boolean run){
    _run = run;
}

@Override
public void run(){

    while(_run){
        Canvas c=null;
        try{
            c = _surfaceHolder.lockCanvas(null);
            synchronized(_surfaceHolder){
                    _firstThread.onDraw(c);
            }


        } finally {
        }
            if (c!=null){
                _surfaceHolder.unlockCanvasAndPost(c);
            }
        }
    }

}

我有一个与上面相同但名称不同的secondThread 类，它调用secondCircle 的onDraw()。

当我运行这个程序时，它只显示蓝色圆圈，而不显示红色圆圈。这是为什么呢？

Answer 1

添加视图时，请使用布局参数添加它们。第一个视图可能会填充父视图，而没有为第二个视图留下空间。

你可以做类似的事情

LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    layout.addView(first,p);
    layout.addView(second,p);