import java.util.*;
    import java.io.*;
    import java.util.regex.*;

    class Program {
    public static void main (String[] args) throws java.lang.Exception	{
    
    String subject = "01:aa,bb,02:cc,03:dd,04:ee";
    String[] arrayOfPairs = subject.split(",(?=\\d{2}:)");
    System.out.println("\n" + "*** Splits ***");
    for (String split : arrayOfPairs) System.out.println(split);
 
    } // end main
    } // end Program