Extraction Integers and Charachters from String : i am solving mathematical expression problem using Stack Data Structure and i get stuck at extracting numbers and math signs from the string. What i want to do is to make a program to evaluate a given expression. 

My question is, how to extract all numbers and signs from string into new string array.

    Input: 12*1*145*2+8*1*1+2*3+2+4

The new string array should be:

    String[] expArray={"12","*","1","*","145","*","2","+","8","*","1","*","1","+","2","*","3","+","2","+","4"}

I tried with nextInt(), split(), next(), nextByte() but it was unsuccessful.
Don't worry about anything else. I just mentioned the Problem just to got clear on what i am talking about.

Hope i am clear. If question feel free to ask. I need this urgent.
Thanks in advice

UPDATE: I don't need solution with building integers like array[i]*10+array[i+1] or something similar. What i need is more optimal solution.