Java Substring from multiline string

There is a number of ways to accomplish this but the easiest is most likely:

String inputString ="URL: www.someurl.com\n" +
                    "id:12345678\n" +
                    "dial:+98765432\n" +
                    "code:0192837465\n" +
                    "password:abc\n" +
                    "\n" +
                    "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" +
                    "some line here\n" +
                    "~~~~~~~~~~~~~~~~~~~~~~~~~~~~";

if (inputString.contains("\r\n")) {
    inputString = inputString.substring(0, inputString.indexOf("\r\n\r\n")).trim();
}
else {
    inputString = inputString.substring(0, inputString.indexOf("\n\n")).trim();
}
System.out.println(inputString);

Another simple way to accomplish this is:

String inputString ="URL: www.someurl.com\n" +
                    "id:12345678\n" +
                    "dial:+98765432\n" +
                    "code:0192837465\n" +
                    "password:abc\n" +
                    "\n" +
                    "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" +
                    "some line here\n" +
                    "~~~~~~~~~~~~~~~~~~~~~~~~~~~~";
String[] stringParts = inputString.split("\n\n|\r\n\r\n");
inputString = stringParts[0];
System.out.println(inputString)

And yet another way this can be accomplished is by utilizing the Scanner class:

String inputString ="URL: www.someurl.com\n" +
                    "id:12345678\n" +
                    "dial:+98765432\n" +
                    "code:0192837465\n" +
                    "password:abc\n" +
                    "\n" +
                    "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" +
                    "some line here\n" +
                    "~~~~~~~~~~~~~~~~~~~~~~~~~~~~";
StringBuilder sb = new StringBuilder();
Scanner scan = new Scanner(inputString);
String line;
while (scan.hasNextLine()) {
    line = scan.nextLine();
    if (line.equals("")) {
        break;
    }
    sb.append(line).append(System.lineSeparator());
}
inputString = sb.toString().trim();
System.out.println(inputString);

If you want to use a Regular Expression (RegEx) along with Pattern/Matcher classes which is part of the java.util.regex package then you can try this:

String inputString = "URL: www.someurl.com\n"
                   + "id:12345678\n"
                   + "dial:+98765432\n"
                   + "code:0192837465\n"
                   + "password:abc\n"
                   + "\n"
                   + "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n"
                   + "some line here\n"
                   + "~~~~~~~~~~~~~~~~~~~~~~~~~~~~";

Pattern pattern = Pattern.compile("(.*?\n{2}[\r]?)", Pattern.DOTALL);
Matcher m = pattern.matcher(inputString);
String newString = "";
if (m.find()) {
     newString = (m.group().trim());
}
System.out.println(newString);

What is this Regular Expression? - "(.*?\n{2}[\r]?)"

• ( : Capturing Group #1 (start) - Groups multiple tokens together and creates a capture group for extracting a substring or using a backreference. This is the open parentheses indicating the start of a group.
• . : Dot - Matches any character except linebreaks.
• * : Quantifier - Matches 0 or more of the preceding token.
• ? : Lazy - Makes the preceding quantifier lazy, causing it to match as few characters as possible. By default, quantifiers are greedy, and will match as many characters as possible.
• \n : Escaped Character - Matches a LINE FEED character (char code 10).
• {2} : Quantifier - Matches the specified quantity of the previous token. For example, {1,3} will match 1 to 3. {3} will match exactly 3. {3,} will match 3 or more.
• [ : Character Set (start) - Match any character in the set. This open Square bracket starts the Character Set.
• \r: Escaped Character - Contained within the Character Set - Matches a CARRIAGE RETURN character (char code 13).
• ] : **Character Set (end) - Match any character in the set. This close Square bracket ends the Character Set.
• ? : Quantifier - Matches 0 or 1 of the preceding token, effectively making it optional. The preceding token would be the \r contained within the Character Set.
• ) : Capturing Group #1 (end) - Groups multiple tokens together and creates a capture group for extracting a substring or using a backreference. This is the close parentheses indicating the end of a group.

    public static void main(String[] args) {
    String myString = "URL: www.someurl.com\n" +
            "id:12345678\n" +
            "dial:+98765432\n" +
            "code:0192837465\n" +
            "password:abc\n" +
            "\n" +
            "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" +
            "some line here\n" +
            "~~~~~~~~~~~~~~~~~~~~~~~~~~~~";
    String[] split = myString.split("\\n\\n");
    System.out.println(split[0]);
}