java.util.regex

Interface MatchResult

All Known Implementing Classes:

Matcher

public interface MatchResult

The result of a match operation.

This interface contains query methods used to determine the results of a match against a regular expression. The match boundaries, groups and group boundaries can be seen but not modified through a MatchResult.

Since:

1.5

Author:

Michael McCloskey

See Also:

Matcher

Method Summary

Methods

Modifier and Type	Method and Description
int	end() Returns the offset after the last character matched.
int	end(int group) Returns the offset after the last character of the subsequence captured by the given group during this match.
String	group() Returns the input subsequence matched by the previous match.
String	group(int group) Returns the input subsequence captured by the given group during the previous match operation.
int	groupCount() Returns the number of capturing groups in this match result's pattern.
int	start() Returns the start index of the match.
int	start(int group) Returns the start index of the subsequence captured by the given group during this match.

Method Detail

start

int start()

Returns the start index of the match.

Returns:

The index of the first character matched

Throws:

IllegalStateException - If no match has yet been attempted, or if the previous match operation failed

start

int start(int group)

Returns the start index of the subsequence captured by the given group during this match.

Capturing groups are indexed from left to right, starting at one. Group zero denotes the entire pattern, so the expression m.start(0) is equivalent to m.start().

Parameters:

group - The index of a capturing group in this matcher's pattern

Returns:

The index of the first character captured by the group, or -1 if the match was successful but the group itself did not match anything

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

end

int end()

Returns the offset after the last character matched.

Returns:

@return The offset after the last character matched

Throws:

IllegalStateException - If no match has yet been attempted, or if the previous match operation failed

end

int end(int group)

Returns the offset after the last character of the subsequence captured by the given group during this match.

Capturing groups are indexed from left to right, starting at one. Group zero denotes the entire pattern, so the expression m.end(0) is equivalent to m.end().

Parameters:

group - The index of a capturing group in this matcher's pattern

Returns:

The offset after the last character captured by the group, or -1 if the match was successful but the group itself did not match anything

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

group

String group()

Returns the input subsequence matched by the previous match.

For a matcher m with input sequence s, the expressions m.group() and s.substring(m.start(), m.end()) are equivalent.

Note that some patterns, for example a*, match the empty string. This method will return the empty string when the pattern successfully matches the empty string in the input.

Returns:

The (possibly empty) subsequence matched by the previous match, in string form

Throws:

IllegalStateException - If no match has yet been attempted, or if the previous match operation failed

group

String group(int group)

Returns the input subsequence captured by the given group during the previous match operation.

For a matcher m, input sequence s, and group index g, the expressions m.group(g) and s.substring(m.start(g), m.end(g)) are equivalent.

Capturing groups are indexed from left to right, starting at one. Group zero denotes the entire pattern, so the expression m.group(0) is equivalent to m.group().

If the match was successful but the group specified failed to match any part of the input sequence, then null is returned. Note that some groups, for example (a*), match the empty string. This method will return the empty string when such a group successfully matches the empty string in the input.

Parameters:

group - The index of a capturing group in this matcher's pattern

Returns:

The (possibly empty) subsequence captured by the group during the previous match, or null if the group failed to match part of the input

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

groupCount

int groupCount()

Returns the number of capturing groups in this match result's pattern.

Group zero denotes the entire pattern by convention. It is not included in this count.

Any non-negative integer smaller than or equal to the value returned by this method is guaranteed to be a valid group index for this matcher.

Returns:

The number of capturing groups in this matcher's pattern