Split Java String by New Line

Question

I'm trying to split text in a JTextArea using a regex to split the String by \n However, this does not work and I also tried by \r\n|\r|n and many other combination of regexes. Code:

public void insertUpdate(DocumentEvent e) {     String split[], docStr = null;     Document textAreaDoc = (Document)e.getDocument();      try {         docStr = textAreaDoc.getText(textAreaDoc.getStartPosition().getOffset(), textAreaDoc.getEndPosition().getOffset());     } catch (BadLocationException e1) {         // TODO Auto-generated catch block         e1.printStackTrace();     }      split = docStr.split("\\n"); } 

Answer 1

This should cover you:

String lines[] = string.split("\\r?\\n"); 

There's only really two newlines (UNIX and Windows) that you need to worry about.

Answer 2

String#split​(String regex) method is using regex (regular expressions). Since Java 8 regex supports \R which represents (from documentation of Pattern class):

Linebreak matcher
\R         Any Unicode linebreak sequence, is equivalent to \u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029]

So we can use it to match:

• \u000D\000A -> \r\n pair
• \u000A -> line feed (\n)
• \u000B -> line tabulation (DO NOT confuse with character tabulation \t which is \u0009)
• \u000C -> form feed (\f)
• \u000D -> carriage return (\r)
• \u0085 -> next line (NEL)
• \u2028 -> line separator
• \u2029 -> paragraph separator

As you see \r\n is placed at start of regex which ensures that regex will try to match this pair first, and only if that match fails it will try to match single character line separators.

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So if you want to split on line separator use split("\\R").

If you don't want to remove from resulting array trailing empty strings "" use split(regex, limit) with negative limit parameter like split("\\R", -1).

If you want to treat one or more continues empty lines as single delimiter use split("\\R+").