安卓设置自定义view宽度高度

PianoView piano = new PianoView(this);
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
        ViewGroup.LayoutParams.MATCH_PARENT, // 宽度设为匹配父容器
        200 // 高度设为 200 像素
);
piano.setLayoutParams(params);
setContentView(piano);