How to split this string in Java regex? -

this string:

string strpro = "(a0(a1)(a2 , on)...(an))"; 

content in son-() may "", or value of strpro, or pattern, recursively, sub-() sub-tree.

expected result:

str1 "a0(a1)" str2 "(a2 , on)" ... strn "(an)" 

str1, str2, ..., strn e.g. elements in array

how split string?

you can use substring() rid of outer paranthesis, , split using lookbehind , lookahead (?<= , ?=):

string strpro = "(a0(a1)(a2 , on)(an))"; string[] split = strpro.substring(1, strpro.length() - 1).split("(?<=\\))(?=\\()"); system.out.println(arrays.tostring(split)); 

this prints

[a0(a1), (a2 , on), (an)]