Question

The following code works:

String str= "test with foo hoo";
Pattern pattern = Pattern.compile("foo");
Matcher matcher = pattern.matcher(str);

if(matcher.find()) { ... }

But this example does not:

if(Pattern.matches("foo", str)) { ... }

And neither this version:

if(str.matches("foo")) { ... }

In the real code, str is a chunk of text with multiple lines if that is treated differently by the matcher, also in the real code, replace will be used to replace a string of text.

Anyway, it is strange that it works in the first version but not the other two versions.

Edit

Ok, I realise that the behaviour is the same in the first example if if(matcher.matches()) { ... } is used instead of matcher.find. I still cannot make it work for multiline input but I stick to the Pattern.compile/Pattern.matcher solution anyway.

Answer 1

Your last couple of examples fail because matches adds an implicit start and end anchor to your regular expression. In other words, it must be an exact match of the entire string, not a partial match.

You can work around this by using .*foo.* instead. Using Matcher.find is more flexible solution though, so I’d recommend sticking with that.