1如果一个自定义view要在短时间被多次调用，会造成多次读取xml和findViewById，所以动态添加控件、属性

RelativeLayout：

private void initView() {

Button btn1 = new Button(this.getContext());

btn1.setId(1);

RelativeLayout.LayoutParams params1 = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

params1.addRule(ALIGN_PARENT_LEFT);

btn1.setText("1");

this.addView(btn1,params1);

Button btn2 = new Button(this.getContext());

btn2.setId(2);

RelativeLayout.LayoutParams params2 = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

params2.addRule(RIGHT_OF,btn1.getId());

btn2.setText("2");

this.addView(btn2,params2);

Button btn3 = new Button(this.getContext());

btn3.setId(3);

RelativeLayout.LayoutParams params3 = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

params3.addRule(RIGHT_OF,btn2.getId());

btn3.setText("3");

this.addView(btn3,params3);

this.setLayoutParams(new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT));

}

 

不setId的话，getId默认返回－1，无法使用RIGHT_OF