android - 开始一个新的随机活动

Question

单击按钮后如何开始随机活动？启动按钮后必须以随机模式启动 Activity 1、Activity 2 或 Activity 3。我该怎么办？

 public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    start = (Button) findViewById (R.id.bstart);

    start.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            //here must start a random activity..
        }
    });