RelativeLayout代码中设置属性

Question

[size=x-large]RelativeLayout.LayoutParams lp2 = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
lp2.addRule(RelativeLayout.[color=red]POSITION_BELOW[/color], ID_BTN1);[/size]
为什么我自己写怎么没有RelativeLayout.POSITION_BELOW，只有RelativeLayout.BELOW，这两种设置的效果不一样，一种是并排在下面，一种的重叠的下面？请教高手！

Answer 1

我刚测试了一下，用below是可以实现的，只是你忽略了一个东西，注意一下这个ID_BTN1的值，你会发现，它的值是-1，是因为你并没有给你这个view setId()

    RelativeLayout rl=new RelativeLayout(this);
    rl.setBackgroundColor(Color.BLUE);
    Button btn1=new Button(this);
    btn1.setText("btn1");
    System.out.println(btn1.getId());
    btn1.setId(123);
    Button btn2=new Button(this);
    btn2.setText("btn2");
    rl.addView(btn1);
    rl.addView(btn2);

    RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
    lp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
    lp.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);
    btn1.setLayoutParams(lp);
    lp=new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
    lp.addRule(RelativeLayout.BELOW, btn1.getId());
    btn2.setLayoutParams(lp);
    setContentView(rl);