I am making a program that lets a user input a chemical for example C9H11N02. When they enter that I want to split it up into pieces so I can have it like C9, H11, N, 02. When I have it like this I want to make changes to it so I can make it C10H12N203 and then put it back together. This is what I have done so far. using the regular expression I have used I can extract the integer value, but how would I go about get C10, H11 etc..? System.out.println("Enter Data"); Scanner k = new Scanner( System.in ); String input = k.nextLine(); String reg = "\\s\\s\\s"; String [] data; data = input.split( reg ); int m = Integer.parseInt( data[0] ); int n = Integer.parseInt( data[1] );