使用JOptionPane计算java中的连续字母？

Question

I'm trying to count consecutive letters in java using JOptionPane and when I try to compile and run my code I get this:

exception in thread main java.lang.StringIndexOutOfBoundsException: String index out of range: 5

I feel like I have most of it down so I'm not exactly sure what's wrong here. Any help would be appreciated.

My code:

import javax.swing.JOptionPane;

public class Project {

    public static void main(String[] args) {

        String input = JOptionPane.showInputDialog("Enter a string...");

        while (true) {

            if (input.equals("Stop")) System.exit(0);

            else {
                int count = 0;
                int len = input.length();
                for (int i = 0; i < len; i++) {
                    if (input.charAt(i) == input.charAt(i + 1)) count++;
                }

                JOptionPane.showMessageDialog(null, "There are " +
                    count + "pairs of consecutive letters.");

                input = JOptionPane.showInputDialog(null,
                    "Enter a string...");
            }
        }
    }
}

Answer 1

Problem is:

input.charAt(i + 1)

This will throw an error because when you are at the last element of the array it will try and get the next element but there isn't one. Consider revising your logic slightly.

In your for loop you could do:

for (int i = 0; i < len - 1; i++) {

Answer 2

The JOptionPane has absolutely nothin to do with that, you should fix your title. The problem is here :

for (int i = 0; i < len; i++) {
   if (input.charAt(i) == input.charAt(i + 1)) count++;
}

replace that piece of code with

for (int i = 0; i < len - 1 ; i++) {
    if (input.charAt(i) == input.charAt(i + 1)) count++;
}

This is a basic error, it is important for an efficient programer to be able to deal with this alone and quickly.