Measure scanner input length

Question

I want a scanner that will ask the user to input a character, however if more than one character is entered it should prompt the user again for only one character.

This is what I have so far:

System.out.print("(Player 2) Guess a letter: ");
Scanner letterScan = new Scanner(System.in);
while(letterScan.nextLine().length()>1)
{
    System.out.print("(Player 2) Please guess only one letter: ");

    //char inputLetter = letterScan.next().charAt(0);
}
char inputLetter = letterScan.next().charAt(0);
System.out.println("letter: " + inputLetter);

The only problem is, this is the output when I run it:

(Player 2) Guess a letter: asfa
(Player 2) Please guess only one letter: a
s
letter: s

You see the third line? It's asking for another prompt. I want to get rid of that and make it so that it uses the letter in the 2nd line from the output instead. Any ideas?

Answer 1

The line letterScan.next() is reading an additional character after you get your correct line. You need to save the first input of 1 character you receive, like so:

System.out.print("(Player 2) Guess a letter: ");
Scanner letterScan = new Scanner(System.in);
String line = "";
//just check for one character.
while((line=letterScan.nextLine()).length()!=1)
{
    System.out.print("(Player 2) Please guess only one letter: ");
}
char inputLetter = line.charAt(0);
System.out.println("letter: " + inputLetter);

Also change your while loop to just check the input has 1 character, otherwise the player could just press enter and your code would crash as the input would have 0 characters. The code above does this too.

Answer 2

its because this line:

char inputLetter = letterScan.next().charAt(0);

remove the above line & change this statement:

while(letterScan.nextLine().length()>1)

to

String line = letterScan.nextLine();
while(line.length()>1)