public String group (int group)

Implementing: java.util.regex.MatchResult

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.

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