Question

I need to remove all characters from the given string except for several which should left. How to do that with regexp?

Simple test: characters[1, a, *] shouldn’t be removed, all other should from string “asdf123**”.

Answer 1

There is: ^ in a set.

You should be able to do something like:

text = text.replaceAll("[^1a*]", "");

Full sample:

public class Test
{
    public static void main(String[] args)
    {
        String input = "asdf123**";
        String output = input.replaceAll("[^1a*]", "");
        System.out.println(output); // Prints a1**
    }
}