我只能输入字母而不是数字时遇到麻烦

Question

For my project I need to input a first and last name with no numbers but I simply can't find anything online. If you could help, that would be terrific.

Also if you have the time, I need to flip the first and last name with a comma when the user inputs them.

    import java.io.BufferedReader;
    import java.io.InputStreamReader;
    import java.io.IOException;

    public class PhoneListr {

public static void main (String[] args) throws IOException {
    String firstName;
    String lastName;
    System.out.println ("Please enter your first name:");
    firstName = PhoneList ("");
    System.out.println ("Please enter your last name:");
    lastName = PhoneList ("");
    System.out.println ("Your full name is: " + lastName + "," + firstName);
}

public static String PhoneList (String input) throws IOException {
    boolean continueInput = false;

    while (continueInput == false) {

            BufferedReader bufferedReader = new BufferedReader (new InputStreamReader (System.in));
            input = bufferedReader.readLine();
            continueInput = true;

            if(input.matches("[a-zA-Z]+")) {
                continueInput = true;
                    }
                  else {
                 System.out.println ("Error, you may only use the alphabet");
                 continueInput = false;
        }
    }
    return input;
}

}

Answer 1

use String.matches(regex) :

    if(input.matches("[a-zA-Z]+")) {
     System.out.println("your input contains no numerics");
        }
      else {
     System.out.println("only alphabets allowed");
}

the above regex checks a through z, or A through Z, inclusive (range).

Answer 2

For this type of string matching you need to use Regular Expressions, or "RegEx"es. It is a very big topic to cover but here's an introduction . RegExes are tools used to test whether strings match certain criteria, and/or to pull certain patterns out of that string or replace certain parts that match those patterns with something else.

Here is an example using a RegEx to test whether your input contains a digit:

if(input.matches("\\d")) {
 // matched a digit, do something
}

Answer 3

Based on OP problem and clarification here are few suggestions.

Chaitanya solution handles the check for only alphabets perfectly.

About the neglected areas of problem :

i would advice you to make two variable firstName and lastName inside the main()

String firstName;
String lastName;

Change retun type of method phoneList() to String

return the entered name input insted of number inside the method phoneList ( dont actually see why you are returning number) and store it inside the firstName and lastName

System.out.println ("Please enter your first name:");
firstName = PhoneList (0);
System.out.println ("Please input your last name:");
lastNamr =PhoneList (0);

now to print it in the "comma format" use

  System.out.println("full name is: " +lastName+ "," +firstName);

As i read your program again , its a mess!!

About the method phoneList()

1. Use regex condition to set continueInput to true/flase and not exploit execptions.

Ps I would appreciate "editing" to post , if any fellow member find any mistakes above, using a mobile, not sure about formatting etc. Thanks. :-) (y)

Answer 4

You can also use

if(input.matches("[^0-9]"))
{
System.out.println("Don't input numbers!");
continueInput = false;}

Can't understand what 2nd question asks. For answer what I get from your 2nd question is like this. In main function change the code like this

String first_name = null;
String last_name = null;
System.out.println ("Please enter your first name:");
first_name = PhoneList();
System.out.println ("Please input your last name:");
second_name = PhoneList();
System.out.println (second_name+","+first_name);

then in PhoneList function last line should be changed to

return input;

Please check for a link ! for more info

Answer 5

You can add a check by passing the argument to method StringUtils.isNumeric

This returns true if the String entered is numeric