Java RegEx - Regular expression to split a paragraph with start and end

Question

I am new to java regex.Please help me. Consider the below paragraph,

Paragraph :

            Name abc
            sadghsagh
            hsajdjah N         


        

Answer 1

The following should also do if you want to keep both Name and !!! in the results.

String[] parts = string.split("(?=(Name|!!!))");

Edit: here's the corrected version:

String[] parts = string.split("(?<=!!!)\\s*(?=Name)");

This will split on any whitespace between !!! and Name and nothing else; hereby keeping the both parts. If you don't want to split on !!!Name, then replace \\s* by \\s+ to allow a one-to-many match instead of zero-to-many match.

Edit2: attached an example of the input/output. Input is copied from the topicstart:

String string = "Name hhhhh class0" + "\n" + "HHHHHHHHHHHHHHHHHH" + "\n" + "!" + "\n"
    + "Name TTTTT TTTT" + "\n" + "GGGGGG UUUUU IIII" + "\n" + "!" + "\n"
    + "Name JJJJJ WWWW" + "\n" + "IIIIIIIIIIIIIIIIIIIII" + "\n" + "!" + "\n"
    + "RRRRRRRRRRR TTTTTTTT" + "\n" + "HHHHHH" + "\n" + "JJJJJ 1 Name class1" + "\n"
    + "LLLLL 5 Name class5" + "\n" + "!" + "\n" + "OOOOOO HHHH FFFFFF" + "\n"
    + "service 0 Name class12" + "\n" + "!" + "\n" + "JJJJJ YYYYYY 3/0" + "\n" + "KKKKKKK"
    + "\n" + "UUU UUU UUUUU" + "\n" + "QQQQQQQ" + "\n" + "!";

String[] parts = string.split("(?<=!)\\s*(?=Name)");
for (String part : parts) {
    System.out.println(part);
    System.out.println("---------------------------------");
}

Output:

Name hhhhh class0
HHHHHHHHHHHHHHHHHH
!
---------------------------------
Name TTTTT TTTT
GGGGGG UUUUU IIII
!
---------------------------------
Name JJJJJ WWWW
IIIIIIIIIIIIIIIIIIIII
!
RRRRRRRRRRR TTTTTTTT
HHHHHH
JJJJJ 1 Name class1
LLLLL 5 Name class5
!
OOOOOO HHHH FFFFFF
service 0 Name class12
!
JJJJJ YYYYYY 3/0
KKKKKKK
UUU UUU UUUUU
QQQQQQQ
!
---------------------------------

Looks fine?

Answer 2

Try:

import java.util.*;
import java.util.regex.*;

public class Main { 

    public static String[] tokenize(String text, String start, String end) {
        // old line:
        //Pattern p = Pattern.compile("(?s)"+Pattern.quote(start)+".*?"+Pattern.quote(end));
        // new line:
        Pattern p = Pattern.compile("(?sm)^"+Pattern.quote(start)+".*?"+Pattern.quote(end)+"$");

        Matcher m = p.matcher(text);
        List<String> tokens = new ArrayList<String>();
        while(m.find()) {
            tokens.add(m.group());
        }
        return tokens.toArray(new String[]{});
    }

    public static void main(String[] args) {
        String text = "Name abc" + "\n" +
            "sadghsagh"          + "\n" +
            "hsajdjah Name"      + "\n" +
            "ggggggggg"          + "\n" +
            "!!!"                + "\n" +
            "Name ggg"           + "\n" +
            "dfdfddfdf Name"     + "\n" +
            "!!!"                + "\n" +
            "Name hhhh"          + "\n" +
            "sahdgashdg Name"    + "\n" +
            "asjdhjasdh"         + "\n" +
            "sadasldkalskd"      + "\n" +
            "asdjhakjsdhja"      + "\n" +
            "!!!";
        String[] tokens = tokenize(text, "Name", "!!!");
        int n = 0;
        for(String t : tokens) {
            System.out.println("---------------------------\n"+(++n)+"\n"+t);
        }
    }
}

Answer 3

String s = "Name abc sadghsagh hsajdjah !!! Name ggg dfdfddfdf !!! Name hhhh sahdgashdg asjdhjasdh sadasldkalskd asdjhakjsdhja !!!!! ";
String startsWith = "Name";
String endsWith = "!!!";

// non-greedily get all groups starting with Name and ending with !!!
String pattern = String.format("(%s).*?(%s)", Pattern.quote(startsWith), Pattern.quote(endsWith));
System.out.println(pattern);

Matcher m = Pattern.compile(pattern, Pattern.DOTALL).matcher(s);
while (m.find()) 
  System.out.println(m.group());

output:

(\QName\E).*?(\Q!!!\E)
Name abc sadghsagh hsajdjah !!!
Name ggg dfdfddfdf !!!
Name hhhh sahdgashdg asjdhjasdh sadasldkalskd asdjhakjsdhja !!!