Switch语句处于循环中，重复次数未知

Question

嗨，我正在做一个小任务，我需要构建一个未知重复次数的循环。我的代码有问题，当用户输入字符时，输出将无限显示。我该如何解决？

String[] action = {"x", "u", "d", "l", "r", "s", "h", "e"}; 

        System.out.println("Please enter an action");

    String input = sc.next();

    char selection;

        do{
            selection = input.charAt(0);

        switch(selection){

            case 'x': System.out.print("Bye!"); 
                break;
            case 'u' : System.out.print("You go one square up.");
                break;
            case 'd': System.out.print("You go one square down.");
                break;
            case 'l': System.out.print("You go one square left.");
                break;  
            case 'r': System.out.print("You go one square right.");
                break;      
            case 's': System.out.print("You search the square for treasure. You find nothing.");
                break;  
            case 'h': System.out.print("You hide, waiting for enemies to come by. It gets boring after about an hour and a half, so you give up.");
                break;  
            case 'e': System.out.print("You eat some food. You regain 0 hit points");
                break;
            case 'z': 
                break;
            default: 
                System.out.println("I dont understand");
                break;
        }
        }
            while (selection != 'z');
        ```

Answer 1

do{
  String input = sc.next();
  selection = input.charAt(0);

  switch(selection){
  // rest of the code

}

Answer 2