Infinite Loop not working

Question

The code works the first time through. But after that, the output doesnt work. The main goal of this is to create an infinite loop, of asking a user for a phrase, then a letter. Then, to output the number of occurences of the letter in the phrase. Also - - how would i go about breaking this loop by entering a word?

Scanner in = new Scanner(System.in);

for (;;) {

    System.out.println("Enter a word/phrase");
    String sentence = in.nextLine();

    int times = 0;

    System.out.println("Enter a character.");
    String letter = in.next();

    for (int i = 0; i < sentence.length(); i++) {
        char lc = letter.charAt(0);
        char sc = sentence.charAt(i);
        if (lc == sc) {
            times++;
        }
    }
    System.out.print("The character appeared:" + times + " times.");
}

the loop would break when the user enters "quit" as their phrase/word — N00B, Nov 03 '13 at 21:31
If you want to use `nextLine` and `next` then you probably should read [Scanner issue when using nextLine after nextXXX](http://stackoverflow.com/questions/7056749/scanner-issue-when-using-nextline-after-nextxxx) — Pshemo, Nov 03 '13 at 21:37

score 2 · Accepted Answer · answered Nov 03 '13 at 21:31

Remove the for loop and replace it with a while.

The while loop should check for a phrase and it will drop out automatically when the phrase is met.

So something like

while (!phraseToCheckFor){
// your code
}

This sounds like homework so I won't post all the code but this should be enough to get you started.

score 0 · Answer 2 · answered Nov 03 '13 at 21:30

If you need an infinite loop, just do this:

for(;;) {  //or while(true) {
    //insert code here
}

You can break the loop by using the break statement, for example like this:

for(;;) {
    String s = in.nextLine();
    if(s.isEmpty()) {
        break; //loop terminates here
    }
    System.out.println(s + " isn't empty.");
}

score 0 · Answer 3 · answered Nov 03 '13 at 21:36

In order for your program to run correctly, you need to consume the last new line character. You can do this by adding a call to nextLine. Working example,

public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        for (;;) {

            System.out.println("Enter a word/phrase");
            String sentence = in.nextLine();

            if (sentence.trim().equals("quit")) {
                break;
            }

            int times = 0;


            System.out.println("Enter a character.");
            String letter = in.next();

            for (int i = 0; i < sentence.length(); i++) {
                char lc = letter.charAt(0);
                char sc = sentence.charAt(i);
                if (lc == sc) {
                    times++;
                }
            }
            System.out.println("The character appeared:" + times + " times.");
            in.nextLine();//consume the last new line
        }
    }

Don't give OP ready code. Let him improve his programming abilities by showing his mistakes, not correcting them. — Pshemo, Nov 03 '13 at 21:39

Infinite Loop not working

3 Answers3