The start(int group) method of Matcher Class is used to get the start index of the match result already done, from the specified group.
public int start(int group)
Parameters: This method takes a parameter group which is the group 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 group.
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 index.
Below examples illustrate the Matcher.start() method:
Current Matcher: java.util.regex.Matcher[pattern=(G*s) region=0,13 lastmatch=]
Current Matcher: java.util.regex.Matcher[pattern=(G*G) region=0,19 lastmatch=]
Reference: Oracle Doc
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