Question

我是Java的新手，我想知道如何检查用户是否只键入了他/她姓名的字母。如果他们没有再问他们的姓名。

System.out.print("Welcome - What is your family's surname? ");
familySurname = keyboard.nextLine();
while (familySurname.isEmpty())  
{
    System.out.print("Invalid name - What is your family's surname? ");
    familySurname = keyboard.nextLine();
    if (familySurname.matches("[a-zA-Z]"))
    {
        System.out.println("Invalid Input.");
    }
}

这是我到目前为止的代码，但它仍在接受数字。

Answer 1

你的循环条件应该是：

 while (!familySurname.matches("[a-zA-Z]+")){
     System.out.print("Invalid name - What is your family's surname? ");
     familySurname = keyboard.nextLine();
 }

Answer 2

if (!familySurname.matches("[a-zA-Z]+")) // need ! and +

Answer 3

或速度 -

public static boolean isAlpha(final String value) {

    if(value == null || value.isEmpty()){
        return false;
    }

    char[] chars = value.toCharArray();

    for (char c : chars) {
        if(!Character.isLetter(c)) {
            return false;
        }
    }

    return true;
}

您的代码段可以修改为 -

while (!isAlpha(familySurname)){

    System.out.print("Invalid name - What is your family's surname? ");
    familySurname = keyboard.nextLine();

}

Answer 4

System.out.print("Welcome - What is your family's surname? ");
    familySurname = keyboard.nextLine();
    while (familySurname.isEmpty())  
    {
        System.out.print("Invalid name - What is your family's surname? ");
        familySurname = keyboard.nextLine();
        if (!familySurname.isLetter(source.charAt(i)))
        return "";
    }

Answer 5

你不想捕捉和修剪它吗？

System.out.print("Welcome - What is your family's surname? ");
String familySurname = "";
while (familySurname.length() == 0) { // while we don't have a surname.
  if (keyboard.hasNextLine()) { // check that there is a line of input.
    familySurname = keyboard.nextLine().trim(); // get the line and trim() it.
    for (char c : familySurname.toCharArray()) {
      if (!Character.isLetter(c)) { // Test for not a letter.
        System.out.print("Invalid name - What is your family's surname? ");
        familySurname = "";
        break;
      }
    }
  }
}

检查用户是否只将字母放入String中

5 个答案: