Regular Expression pattern search is throwing "java.lang.IllegalStateException"

[Poorav Chaudhari]

I am trying to find the position of string that matches the regular expression in a given 'word'. But for some reason I get the following Exception.

Exception in thread "main" java.lang.IllegalStateException: No match available
at java.util.regex.Matcher.start(Matcher.java:325)
at myworkspace.TestRegEx.<init>(TestRegEx.java:16)
at myworkspace.TestRegEx.main(TestRegEx.java:21)

I have created a small program that demonstrates the problem, posted below. I would really appreciate some input on this. thanks

package myworkspace;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class TestRegEx {

    Pattern bolPattern;

    public TestRegEx() {
        String regex = "(one|two|three|four)+";
        bolPattern = Pattern.compile(regex);
        String str1 = "aoner";
        if (strExists(str1)) {
            Matcher matcher = bolPattern.matcher(str1);
            System.out.println("Start: " + matcher.start());
        }
    }

    public static void main(String[] args) {
        TestRegEx t = new TestRegEx();
    }

    public boolean strExists(String word) {
        Matcher matcher = bolPattern.matcher(word);
        return matcher.find();
    }
}

[Jeff Verdegan]

You'll have better luck if you post your actual code, so that the line numbers in the exception line up with the line numbers posted.

This may mean you'll have to create a separate, smaller program just to demonstrate the problem.


Also, have you tried looking at the docs for Matcher.start(), to understand how to use it correctly, and to see why it might throw that exception? That's generally the best place to start.

[Poorav Chaudhari]

I realized I needed to call the matcher.match() or the matcher.find() method before calling matcher.start().