Java 只有带控件的数字

首先，我是这里的新人。我需要问一个问题

Scanner klavye = new Scanner(System.in);

System.out.println("DDD-DD-DDDD enter bank number digit: ");
String hesapNo = klavye.nextLine();

if(hesapNo.length() != 11) {
   System.out.println("You need to enter number with 11 digit");
}
else {
   if(hesapNo.charAt(3) == '-' && hesapNo.charAt(6) == '-') {
       System.out.println(hesapNo + " is valid");
   }
   else {
      System.out.println(hesapNo + " is not valid");
   }
}

我只想取数字，但如果我这样写： ABC-DC-SMND “计数有效” 我怎样才能解决这个问题

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感谢您的关注。

这可以通过以下简单方法完成：

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您可以使用正则表达式和循环来提示用户直到输入有效

Scanner klavye = new Scanner(System.in);

System.out.println("DDD-DD-DDDD enter bank number digit: ");
String hesapNo;
final String regexPattern = "\\d{3}-\\d{2}-\\d{4}";
do {
   hesapNo = klavye.nextLine();
   System.out.println("You need to enter a number with 11 digit with pattern: DDD-DD-DDDD");
}
while(!hesapNo.matches(regexPattern));

System.out.println(hesapNo + " is valid");

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我认为这是一个学习正则表达式的好机会。看见

Scanner klavye = new Scanner(System.in);
String hesapNo;
boolean validInput;

System.out.println("DDD-DD-DDDD enter bank number digit: ");
do {
    hesapNo = klavye.nextLine();
    validInput = hesapNo.matches("\\d{3}-\\d{2}-\\d{4}");
    if (!validInput) { // if invalid input then warn the user
        System.out.println("Your bank number must be in DDD-DD-DDDD format");
    }
} while (!validInput); // loop until a valid input is provided
System.out.println(hesapNo + " is valid");

Scanner klavye = new Scanner(System.in);

System.out.println("DDD-DD-DDDD enter bank number digit: ");
String hesapNo;
final String regexPattern = "\\d{3}-\\d{2}-\\d{4}";
do {
   hesapNo = klavye.nextLine();
   System.out.println("You need to enter a number with 11 digit with pattern: DDD-DD-DDDD");
}
while(!hesapNo.matches(regexPattern));

System.out.println(hesapNo + " is valid");