Regular expression boundary matchers for beginning of line (^) and end of line ($) not working

Question

I have a pattern using ^ and $ to indicate beginning and end of line.

Pattern pattern = Pattern.compile( "^Key2 = (.+)$" );

and input like this:

String text = "Key1 = Twas brillig, and the slithy toves"
  + "\nKey2 = Did gyre and gimble in the wabe."
  + "\nKey3 = All mimsy were the borogroves."
  + "\nKey4 = And the mome raths outgrabe.";

But pattern.matcher( text ).find() returns false.

Shouldn't this work? In the Pattern class documentation, the summary specifies:

Boundary matchers
^  The beginning of a line
$  The end of a line

Answer 1

By default, those symbols match the beginning and end of the entire input sequence.

Further down in that same Pattern class documentation (with emphasis added):

By default, the regular expressions ^ and $ ignore line terminators and only match at the beginning and the end, respectively, of the entire input sequence. If MULTILINE mode is activated then ^ matches at the beginning of input and after any line terminator except at the end of input. When in MULTILINE mode $ matches just before a line terminator or the end of the input sequence.

So you can make ^ and $ work as they are documented in summary table by compiling the pattern with Pattern.MULTILINE:

Pattern pattern = Pattern.compile( "^Key2 = (.+)$", Pattern.MULTILINE );