See if a string contains any characters in it

Question

The problem I'm having is when I check to see if the string contains any characters it only looks at the first character, not the whole string. For instance, I would like to be able to input "123abc" and the characters are recognized so it fails. I also need the string to be 11 characters long and since my program only works with 1 character it cannot go any further.

Here is my code so far:

public static int phoneNumber(int a)
{
   while (invalidinput)
            {
        phoneNumber[a] = myScanner.nextLine();
        
        if (phoneNumber[a].matches("[0-9+]") && phoneNumber[a].length() == 11 )
        {   
            System.out.println("Continue");
            invalidinput = false;
        }
        else
        {
            System.out.print("Please enter a valid phone number: ");
        }
        
    }
    
    return 0;
}

For instance why if I take away the checking to see the phoneNumber.length(), it still only registers 1 character; so, if I enter "12345", it still fails. I can only enter "1" for the program to continue.

If someone could explain how this works to me that would be great.

Answer 1

Your regex and if condition is wrong. Use it like this:

 if ( phoneNumber[a].matches("^[0-9]{11}$") ) {
    System.out.println("Continue");
    invalidinput = false;
 }

This will allow only phoneNumber[a] to be a 11 characters long comprising only digits 0-9.