Matcher start(String) method in Java with Examples
Last Updated :
26 Nov, 2018
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:
import java.util.regex.*;
public class GFG {
public static void main(String[] args)
{
String regex = "\\b(?<Geeks>[A-Za-z\\s]+)" ;
Pattern pattern
= Pattern.compile(regex);
String stringToBeMatched
= "GeeksForGeeks" ;
Matcher matcher
= pattern
.matcher(stringToBeMatched);
MatchResult result
= matcher.toMatchResult();
System.out.println( "Current Matcher: "
+ result);
while (matcher.find()) {
System.out.println(matcher.start( "Geeks" ));
}
}
}
|
Output:
Current Matcher: java.util.regex.Matcher[pattern=\b(?[A-Za-z\s]+) region=0,13 lastmatch=]
0
Example 2:
import java.util.regex.*;
public class GFG {
public static void main(String[] args)
{
String regex = "\\b(?<GFG>[A-Za-z\\s]+)" ;
Pattern pattern
= Pattern.compile(regex);
String stringToBeMatched
= " GFGFGFGFGFGFGFGFGFG" ;
Matcher matcher
= pattern
.matcher(stringToBeMatched);
MatchResult result
= matcher.toMatchResult();
System.out.println( "Current Matcher: "
+ result);
while (matcher.find()) {
System.out.println(matcher.start( "GFG" ));
}
}
}
|
Output:
Current Matcher: java.util.regex.Matcher[pattern=\b(?[A-Za-z\s]+) region=0,22 lastmatch=]
3
Reference: Oracle Doc
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