CODEWITHSUNDEEP
javaregex
Mehdi Ijadnazar
Mehdi Ijadnazar

Reputation: 4961

how to use Matcher.replaceAll in java?

i have a file which contains "(*" and "*)". i want to remove everything between this two char sequences. i used the following code but it didn't do anything with my string.

    String regex = "\\(\\*.*\\*\\)";
    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(input);
    matcher.replaceAll("");

the 'input' is:

(* This program prints out a message. *)

program is

  begin
    write ("Hello, world!");
  end;

Upvotes: 1

Views: 6518

Answers (1)

Paŭlo Ebermann
Paŭlo Ebermann

Reputation: 74760

You need to capture the return value of your matcher - it's replaceAll method returns the replaced String.

Additionally, use a regexp to match what you want to match, this time a parenthesized String. If you don't have some strange inputs, it may look like this:

String regex = "\\(\\*.*\\*\\)";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(input);
String result = matcher.replaceAll("(\\*\\*)");
System.out.println(result);

This regexp in fact captures the whole region from the first comment start to the last comment end, which would usually not be what you want. To let it match non-greedy (reluctantly), use this regexp: \(\*.*?\*\) (with doubled backslashes in Java.)

Upvotes: 2

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