Module java.base
Package 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.

Implementation Note:
Support for named groups is implemented by the default methods start(String), end(String) and group(String). They all make use of the map returned by namedGroups(), whose default implementation simply throws UnsupportedOperationException. It is thus sufficient to override namedGroups() for these methods to work. However, overriding them directly might be preferable for performance or other reasons.
Since:
1.5
See Also:

  • Method Summary

    Modifier and Type
    Method
    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.
    default int
    end(String name)
    Returns the offset after the last character of the subsequence captured by the given named-capturing group during the previous match operation.
    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.
    default String
    group(String name)
    Returns the input subsequence captured by the given named-capturing group during the previous match operation.
    int
    groupCount()
    Returns the number of capturing groups in this match result's pattern.
    default boolean
    hasMatch()
    Returns whether this contains a valid match from a previous match or find operation.
    default Map<String,Integer>
    namedGroups()
    Returns an unmodifiable map from capturing group names to group numbers.
    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.
    default int
    start(String name)
    Returns the start index of the subsequence captured by the given named-capturing group during the previous match operation.

  • Method Details

    • 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

    • start

      default int start(String name)
      Returns the start index of the subsequence captured by the given named-capturing group during the previous match operation.
      Implementation Requirements:
      The default implementation of this method invokes namedGroups() to obtain the group number from the name argument, and uses it as argument to an invocation of start(int).
      Parameters:
      name - The name of a named-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
      IllegalArgumentException - If there is no capturing group in the pattern with the given name
      Since:
      20

    • end

      int end()
      Returns the offset after the last character matched.
      Returns:
      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

    • end

      default int end(String name)
      Returns the offset after the last character of the subsequence captured by the given named-capturing group during the previous match operation.
      Implementation Requirements:
      The default implementation of this method invokes namedGroups() to obtain the group number from the name argument, and uses it as argument to an invocation of end(int).
      Parameters:
      name - The name of a named-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
      IllegalArgumentException - If there is no capturing group in the pattern with the given name
      Since:
      20

    • 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

    • group

      default String group(String name)
      Returns the input subsequence captured by the given named-capturing group during the previous match operation.

      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.

      Implementation Requirements:
      The default implementation of this method invokes namedGroups() to obtain the group number from the name argument, and uses it as argument to an invocation of group(int).
      Parameters:
      name - The name of a named-capturing group in this matcher's pattern
      Returns:
      The (possibly empty) subsequence captured by the named 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
      IllegalArgumentException - If there is no capturing group in the pattern with the given name
      Since:
      20

    • 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

    • namedGroups

      default Map<String,Integer> namedGroups()
      Returns an unmodifiable map from capturing group names to group numbers. If there are no named groups, returns an empty map.
      API Note:
      This method must be overridden by an implementation that supports named groups.
      Implementation Requirements:
      The default implementation of this method always throws UnsupportedOperationException
      Returns:
      an unmodifiable map from capturing group names to group numbers
      Throws:
      UnsupportedOperationException - if the implementation does not support named groups.
      Since:
      20

    • hasMatch

      default boolean hasMatch()
      Returns whether this contains a valid match from a previous match or find operation.
      Implementation Requirements:
      The default implementation of this method always throws UnsupportedOperationException
      Returns:
      whether this contains a valid match
      Throws:
      UnsupportedOperationException - if the implementation cannot report whether it has a match
      Since:
      20