MatchResult start() method in Java with Examples

Last Updated : 27 Nov, 2018
The start() method of MatchResult Interface is used to get the start index of the match result already done. Syntax: 
public int start()
Parameters: This method do not takes any parameter. Return Value: This method returns the index of the first character matched.0 Exception: This method throws IllegalStateException if no match has yet been attempted, or if the previous match operation failed. Below examples illustrate the MatchResult.start() method: Example 1: Java 
// Java code to illustrate start() method

import java.util.regex.*;

public class GFG {
    public static void main(String[] args)
    {

        // Get the regex to be checked
        String regex = "(G*k)";

        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);

        // Get the String to be matched
        String stringToBeMatched = "Geeks";

        // Create a matcher for the input String
        MatchResult matcher
            = pattern
                  .matcher(stringToBeMatched);

        while (((Matcher)matcher).find()) {
            // Get the first index of match result
            System.out.println(matcher.start());
        }
    }
}
Output: 
3
Example 2: Java 
// Java code to illustrate start() method

import java.util.regex.*;

public class GFG {
    public static void main(String[] args)
    {

        // Get the regex to be checked
        String regex = "(G*G)";

        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);

        // Get the String to be matched
        String stringToBeMatched = "GFG";

        // Create a matcher for the input String
        MatchResult matcher
            = pattern
                  .matcher(stringToBeMatched);

        while (((Matcher)matcher).find()) {
            // Get the first index of match result
            System.out.println(matcher.start());
        }
    }
}
Output: 
0
2
=
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