Checking for consecutively repeated characters in java

Question

I am quite new to java. I am wondering if it is possible to check for a certain number of consecutively repeated characters (the 'certain number' being determined by the user) in a string or an index in a string array. So far I have tried

int multiple_characters = 0;
String array1 [] = {"abc","aabc","xyyyxy"};
for (int index = 0; index < array1.length;i++){
   for (int i = 0;i<array1[index].length;i++){
      if (array1[index].charAt(i) == array1[index].charAt(i+1)){
         multiple_characters++;
      }
   }
}

But with this I get a StringIndexOutOfBounds error. I tried fixing this by putting in an extra if statement to make sure i was not equal to the array1[index].length, but this still threw up the same error. Other than the manual and cop-out method of:

if ((array1[index].charAt(i) == array1[index].charAt(i+1) && (array1[index].charAt(i) == array1[index].charAt(i+2))

and repeating however many times, (which would not be great for quick changes to my code), I can't seem to find a solution.

Answer 1

You are getting StringIndexOutOfBoundsException because you are trying to access string.charAt(i + 1) where i goes up to the highest index (i.e. string.length() - 1) of string.

You can do it as follows:

class Main {
    public static void main(String[] args) {
        int multiple_characters = 0;
        int i;
        String array1[] = { "abc", "aabc", "xyyyxy" };
        for (int index = 0; index < array1.length; index++) {
            System.out.println("String: " + array1[index]);
            for (i = 0; i < array1[index].length() - 1; i++) {
                multiple_characters = 1;
                while (array1[index].charAt(i) == array1[index].charAt(i + 1) && i < array1[index].length() - 1) {
                    multiple_characters++;
                    i++;
                }
                System.out.println(array1[index].charAt(i) + " has been repeated consecutively " + multiple_characters
                        + " time(s)");
            }
            if (multiple_characters == 1) {
                System.out.println(array1[index].charAt(i) + " has been repeated consecutively 1 time(s)");
            }
            System.out.println("------------");
        }
    }
}

Output:

String: abc
a has been repeated consecutively 1 time(s)
b has been repeated consecutively 1 time(s)
c has been repeated consecutively 1 time(s)
------------
String: aabc
a has been repeated consecutively 2 time(s)
b has been repeated consecutively 1 time(s)
c has been repeated consecutively 1 time(s)
------------
String: xyyyxy
x has been repeated consecutively 1 time(s)
y has been repeated consecutively 3 time(s)
x has been repeated consecutively 1 time(s)
y has been repeated consecutively 1 time(s)
------------