Question

Is there a way to get the text from a java.util.regex.Matcher? It seems to be write-only. There’s method to set it (reset(CharSequence input)), but no getter (unless I’m overlooking it). There’s also a method for getting the pattern (pattern()), but the text is private without any getter. Why?

Is there a way to find out if a match was attempted other then calling e.g. group() and catching the IllegalStateException?

I’m asking this because I’m using a Matcher as a member and don’t want to repeat the information in additional members, as it clobbers the class needlessly.

Answer 1

As the documentation shows, you’re right : there is no way to get the text from the matcher or to know if a matching operation has been executed.

You could encapsulate the matcher inside a custom rusable class holding the state for you :

public class StatefulMatcher {

    private Matcher matcher;
    private CharSequence input;
    private boolean matchDone;

    public StatefulMatcher(Pattern pattern, String input) {
        this.input = input;
        this.matcher = pattern.matcher(input);
    }

    public void reset(CharSequence input) {
        this.input = input;
        this.matcher.reset(input);
        this.matchDone = false;
    }

    public boolean matches() {
        matchDone = true;
        return matcher.matches();
    }

    public boolean isMatchDone() {
        return matchDone;
    }

    public CharSequence getInput() {
        return input;
    }

    // other methods
}