infinite while loop, .nextLine() user input

Question

Hi I have a question regarding the use of .nextLine and why it skips user input the second time around during the infinite loop. The .next function (letter input) still asks for user input everytime but the .nextLine function (phrase input) does not. Thanks.

    import java.util.Scanner;

    public class Lab6 {
      public static void main (String [] args) {
        Scanner in = new Scanner(System.in);
        String phrase, l;
        char letter;

        while (true) {
          System.out.println("Enter a phrase. Enter 'quit' to quit.");
          phrase = in.nextLine();

          if (phrase.startsWith("quit")) {
            break;
          }

          System.out.println("Enter a letter");
          l = in.next();
          letter = l.charAt(0);

          System.out.println("Phrase entered is: " + phrase);
          System.out.println("Letter entered is: " + letter);

          int i = 0;
          int count = 0;
          while (i < phrase.length()) {
            if (phrase.charAt(i) == letter) {
              count++;
            }
            i++;
          }
          System.out.println(count);
        }
      }    
    }

score 7 · Accepted Answer · answered Nov 04 '12 at 16:45

7

The reason is that Scanner.next() does not consume newline characters from the system input, so the input will be passed through to the statement:

phrase = in.nextLine();

which will now not block having received the input.

answered Nov 04 '12 at 16:45

Reimeus

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Simplest approach would be to consume the newline `l = in.nextLine();`. – Reimeus Nov 04 '12 at 17:05

infinite while loop, .nextLine() user input

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