Divide string into substrings in java

use the pattern: ((\d)\2*)

String input = "1122333344555566778888";
Pattern p = Pattern.compile("((\\d)\\2*)");
Matcher m = p.matcher(input);
while (m.find()) {
    System.out.println("Found " + m.group(1));
}

produces:

11
22
3333
44
5555
66
77
8888

edit: if its numbers as well as spaces and letters use the pattern (([\d\w\s])\2*)

You can use the regular expression of repeating characters:

String input = "1122333344555566778888";
String regex = "(\\w)\\1+";

Matcher m = Pattern.compile(regex).matcher(input);
String[] substrings = new String[input.length()];

int index = 0;

while (m.find())
    substrings[index++] = m.group();

for (int i = 0; i < index; i++)
    System.out.println(substrings[i]);

Output:

11
22
3333
44
5555
66
77
8888

Important Note:

substrings array contains null entries since its length is equal to the input string's length. If your string contains non-repeating sequential characters then this array might not have null entries. Watch on substrings for NullPointerException.

there is no delimiter in this string to be able to use .split(), if you had a delimeter between what you want to have a substring such as 11-22-3333- ... etc, it will be easy to use

String[] splits = asseltClasses.split("-");

Based on BlueBullet's ...

import java.util.regex.*;
import java.util.*;
public class MyTest {

    public static void main(String[] args) {

        String input = "1122333344555566778888";
        String regex = "(\\w)\\1+";

        Matcher m = Pattern.compile(regex).matcher(input);

        List<String> l = new ArrayList<String>();
        while (m.find()) l.add(m.group());

        System.out.println(Arrays.toString(l.toArray()));
    }   
}

Output:

[11, 22, 3333, 44, 5555, 66, 77, 8888]

This beautiful enough? It's just one line...

String parts = input.replaceAll("(.)(?!\\1)", "$1\0").split("\0");

Here's a test:

public static void main(String[] args) {
    String input = "1122333344555566778888";
    String[] parts = input.replaceAll("(.)(?!\\1)", "$1\0").split("\0");
    System.out.println(Arrays.toString(parts));
}

Output:

[11, 22, 3333, 44, 5555, 66, 77, 8888]

Note that there is one very minor hitch with this solution - the character after $1 in the call to replaceAll() must not be possible to have in the input. I chose the null character '\0' (ie hex zero) to be fairly safe.

This is what I would do: Given a string that is not sorted, "ABCABCABC", you can sort it by converting it to a Char[] array, then using Arrays.sort(), turning it into AAABBBCCC.

    public String[] sortThis(String inputData) {
    String input = "ABCABCABC"; //make this whatever you want (or set to inputData)
    String[] temp = new String[input.length()];
    for (int i = 0; i < input.length();i++) //initialize the array, or it prints "null"
        temp[i] = "";
    int index = 0;
    char[] info = input.toCharArray();
    Arrays.sort(info);

    for (int i = 0; i < input.length(); i++) { // fill the temp array
        temp[index] += info[i];
        if(i+1 < input.length())
            if(i < input.length() && info[i] != info[i+1])
                index++;
    }

    String[] answer = new String[index+1]; 
    for(int i = 0; i < index+1; i++) // shorten the array
        answer[i] = temp[i];

    return answer;
    }

Output:

    [AAA, BBB, CCC]

Maybe u want to use this:

var str="1122333344555566778888"; //whatever
b=0;outpt="";
while(b<=18){
if(b==4|b==10|b==18){e=4;p=4}else{e=2;p=2}
outpt+=str.substr(b,e)+", ";b+=p;}
alert(outpt);

Output:

11, 22, 3333, 44, 5555, 66, 77, 8888,