How can I create a regular expression to search strings with a given pattern? For example I want to search all strings that match pattern '*index.tx?'. Now this should find strings with values index.txt,mainindex.txt and somethingindex.txp.
Pattern pattern = Pattern.compile("*.html");
Matcher m = pattern.matcher("input.html");
This code is obviously not working.
You need to learn regular expression syntax. It is not the same as using wildcards. Try this:
Pattern pattern = Pattern.compile("^.*index\\.tx.$");
There is a lot of information about regular expressions here. You may find the program RegexBuddy useful while you are learning regular expressions.
The code you posted does not work because:
. is a special regex character. It means one instance of any character.* means any number of occurrences of the preceding character.therefore, .* means any number of occurrences of any character.
so you would need something like
Pattern pattern = Pattern.compile(".*\\.html.*");
the reason for the \\ is because we want to insert dot, although it is a special regex sign.
this means: match a string in which at first there are any number of wild characters, followed by a dot, followed by html, followed by anything.
* matches zero or more occurrences of the preceding token, so if you want to match zero or more of any character, use .* instead (. matches any char).
Modified regex should look something like this:
Pattern pattern = Pattern.compile("^.*\\.html$");
^ matches the start of the string.* matches zero or more of any char\\. matches the dot char (if not escaped it would match any char)$ matches the end of the string