Matcher start(String) method in Java with Examples
The start(String string) method of Matcher Class is used to get the start index of the match result already done, from the specified string.
Syntax:
public int start(String string)
Parameters: This method takes a parameter string which is the String from which the start index of the matched pattern is required.
Return Value: This method returns the index of the first character matched from the specified string.
Exception: This method throws:
- IllegalStateException if no match has yet been attempted, or if the previous match operation failed.
- IndexOutOfBoundsException if there is no capturing group in the pattern with the given name.
Below examples illustrate the Matcher.start() method:
Example 1:
// 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 = "\\b(?<Geeks>[A-Za-z\\s]+)"; // Create a pattern from regex Pattern pattern = Pattern.compile(regex); // Get the String to be matched String stringToBeMatched = "GeeksForGeeks"; // Create a matcher for the input String Matcher matcher = pattern .matcher(stringToBeMatched); // Get the current matcher state MatchResult result = matcher.toMatchResult(); System.out.println("Current Matcher: " + result); while (matcher.find()) { // Get the first index of match result System.out.println(matcher.start("Geeks")); } }} |
Current Matcher: java.util.regex.Matcher[pattern=\b(?
[A-Za-z\s]+) region=0,13 lastmatch=]
0
Example 2:
// 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 = "\\b(?<GFG>[A-Za-z\\s]+)"; // Create a pattern from regex Pattern pattern = Pattern.compile(regex); // Get the String to be matched String stringToBeMatched = " GFGFGFGFGFGFGFGFGFG"; // Create a matcher for the input String Matcher matcher = pattern .matcher(stringToBeMatched); // Get the current matcher state MatchResult result = matcher.toMatchResult(); System.out.println("Current Matcher: " + result); while (matcher.find()) { // Get the first index of match result System.out.println(matcher.start("GFG")); } }} |
Current Matcher: java.util.regex.Matcher[pattern=\b(?
[A-Za-z\s]+) region=0,22 lastmatch=]
3
Reference: Oracle Doc
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