class StringSplitExample {
    public static void main(String[] args) {
        String st = "Hello_World";
        String str[] = st.split("_");
        for (int i = 0; i < str.length; i++) {
            System.out.println(str[i]);
        }
    }
}

Split String Example in Java

 static void Main(string[] args)
{
    string str = @"N:Pay in Cash++RGI:40++R:200++T:Purchase++IP:N++IS:N++PD:PC++UCP:598.80++UPP:0.00++TCP:598.80++TPP:0.00++QE:1++QS:1++CPC:USD++PPC:Points++D:Y++E:Y++IFE:Y++AD:Y++IR:++MV:++CP:~ ~N:ERedemption++RGI:42++R:200++T:Purchase++IP:N++IS:N++PD:PC++UCP:598.80++UPP:0.00++TCP:598.80++TPP:0.00++QE:1++QS:1++CPC:USD++PPC:Points++D:Y++E:Y++IFE:Y++AD:Y++IR:++MV:++CP:"; 
    System.Text.RegularExpressions.MatchCollection MC = System.Text.RegularExpressions.Regex.Matches(str,@"((RGI|N):.*?)\+\+");
    foreach( Match Foundmatch in MC)
    {
        string[] s = Foundmatch.Groups[1].Value.Split(':');
        Console.WriteLine("Key {0} Value {1} " ,s[0],s[1]);

    }

}