我有一个java程序，我想问用户是创建储蓄银行账户还是活期银行账户。
问题：“是否要创建储蓄帐户（y/n）？”

// Collect Character to validate a savings or current account:
char yes_no = 'a'; //Why can't declare empty char?

System.out.println(ANSI_PURPLE + "Do you want to create a Savings Account (Y/N)?");
System.out.print(ANSI_RESET + " Choose an option > ");

//Check if input is valid. Otherwise allow user to select again:
while(!sc.hasNext()) {
   System.out.println(ANSI_RED + " ERROR: Invalid option! ");
   System.out.print(ANSI_RESET + " Choose an option > ");
   yes_no = sc.next().charAt(0);
}

if (yes_no == 'Y' || yes_no == 'y') {
    System.out.println("Y");
} else if(yes_no == 'N' || yes_no == 'n') {
    System.out.println("N");
} else {
    //run again to collect valid input
}

对于整数，我可以这样做：

// Check if input is valid. Otherwise allow user to select again:
while(!sc.hasNextInt()) {
    System.out.println(ANSI_RED + " ERROR: Invalid option! ");
    System.out.print(ANSI_RESET + " Choose an option > ");
    sc.next();
}

// Store input on variable and process request:
menuInput = sc.nextInt();
menuManager(menuInput);

为什么我不能对角色做类似的事情？
正确回答我的问题：

// Collect Character to validate a savings or current account:
char yes_no = 'a';
System.out.println(ANSI_PURPLE + "Do you want to create a Savings Account (Y/N)?");
System.out.print(ANSI_RESET + " Choose an option > ");
yes_no = sc.next().charAt(0);

// Check if input is valid. Otherwise allow user to select again:
while (!(yes_no == 'Y' || yes_no == 'y' || yes_no == 'N' || yes_no == 'n')) {
    System.out.println(ANSI_RED + " ERROR: Invalid option! ");
    System.out.print(ANSI_RESET + " Choose an option > ");
    yes_no = sc.next().charAt(0);
}
System.out.println("input was " + yes_no);