这个自定义异常怎么用啊

对于自定义异常还没有理解透彻，这个自定义异常怎么用啊，想问一下，谢谢啦

往采纳，谢谢，代码：
==PlayOutOfIndexException.java==

package Test10;

public class PlayOutOfIndexException extends Exception {
    String message;

    public PlayOutOfIndexException(String ErrorMessage){
            this.message = ErrorMessage;
        }

    @Override
    public String getMessage() {
        return message;
    }
}

==Player.java==

package Test10;

public class Player {
    public void play(int index) throws PlayOutOfIndexException {
        if (index > 10) {
            throw new PlayOutOfIndexException("不存在该歌曲");
        } else {
            System.out.println("当前正在播放第" + index + "首歌曲");
        }
    }

    public static void main(String[] args) {
        Player playe = new Player();
        try {
            playe.play(4);
            playe.play(11);
        } catch (PlayOutOfIndexException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
}

效果：

参考下吧，有用可以采纳下

public class PalyOutofException extends RuntimeException{

    public PalyOutofException() {
    }

    public PalyOutofException(String message) {
        super(message);
    }


    public static void main(String[] args) { 
        int index  =20;
        if (index >10){
           throw new PalyOutofException("不存在该歌曲");
        }
    }

}