How to split string in java

Just use the appropriate method: String#split().

String string = "004-034556";
String[] parts = string.split("-");
String part1 = parts[0]; // 004
String part2 = parts[1]; // 034556

Note that this takes a regular expression, so remember to escape special characters if necessary, e.g. if you want to split on period . which means "any character" in regex, use either split("\\.") or split(Pattern.quote(".")).

To test beforehand if the string contains a -, just use String#contains().

if (string.contains("-")) {
    // Split it.
} else {
    throw new IllegalArgumentException("String " + string + " does not contain -");
}