Package java.util.regex

Class Matcher

java.lang.Object
java.util.regex.Matcher
All Implemented Interfaces:
MatchResult
public final class Matcher
extends Object
implements MatchResult
The result of applying a Pattern to a given input. See Pattern for example uses.

  • Method Summary

    Modifier and Type Method Description
    Matcher appendReplacement​(StringBuffer buffer, String replacement)
    Appends a literal part of the input plus a replacement for the current match to a given StringBuffer.
    StringBuffer appendTail​(StringBuffer buffer)
    Appends the (unmatched) remainder of the input to the given StringBuffer.
    int end()
    Returns the index of the first character following the text that matched the whole regular expression.
    int end​(int group)
    Returns the index of the first character following the text that matched a given group.
    protected void finalize()
    Invoked when the garbage collector has detected that this instance is no longer reachable.
    boolean find()
    Returns the next occurrence of the Pattern in the input.
    boolean find​(int start)
    Returns true if there is another match in the input, starting from the given position.
    String group()
    Returns the text that matched the whole regular expression.
    String group​(int group)
    Returns the text that matched a given group of the regular expression.
    int groupCount()
    Returns the number of groups in the results, which is always equal to the number of groups in the original regular expression.
    boolean hasAnchoringBounds()
    Returns true if this matcher has anchoring bounds enabled.
    boolean hasTransparentBounds()
    Returns true if this matcher has transparent bounds enabled.
    boolean hitEnd()
    Returns true if the most recent matching operation attempted to access additional text beyond the available input, meaning that additional input could change the results of the match.
    boolean lookingAt()
    Tries to match the Pattern, starting from the beginning of the region (or the beginning of the input, if no region has been set).
    boolean matches()
    Tries to match the Pattern against the entire region (or the entire input, if no region has been set).
    Pattern pattern()
    Returns the Pattern instance used inside this matcher.
    static String quoteReplacement​(String s)
    Returns a replacement string for the given one that has all backslashes and dollar signs escaped.
    Matcher region​(int start, int end)
    Resets this matcher and sets a region.
    int regionEnd()
    Returns this matcher's region end, that is, the index of the first character that is not considered for a match.
    int regionStart()
    Returns this matcher's region start, that is, the index of the first character that is considered for a match.
    String replaceAll​(String replacement)
    Replaces all occurrences of this matcher's pattern in the input with a given string.
    String replaceFirst​(String replacement)
    Replaces the first occurrence of this matcher's pattern in the input with a given string.
    boolean requireEnd()
    Returns true if the most recent match succeeded and additional input could cause it to fail.
    Matcher reset()
    Resets the Matcher.
    Matcher reset​(CharSequence input)
    Provides a new input and resets the Matcher.
    int start()
    Returns the index of the first character of the text that matched the whole regular expression.
    int start​(int group)
    Returns the index of the first character of the text that matched a given group.
    MatchResult toMatchResult()
    Converts the current match into a separate MatchResult instance that is independent from this matcher.
    String toString()
    Returns a string representing this Matcher.
    Matcher useAnchoringBounds​(boolean value)
    Determines whether this matcher has anchoring bounds enabled or not.
    Matcher usePattern​(Pattern pattern)
    Sets a new pattern for the Matcher.
    Matcher useTransparentBounds​(boolean value)
    Determines whether this matcher has transparent bounds enabled or not.

    Methods inherited from class java.lang.Object

    clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

  • Method Details

    • appendReplacement

      public Matcher appendReplacement​(StringBuffer buffer, String replacement)
      Appends a literal part of the input plus a replacement for the current match to a given StringBuffer. The literal part is exactly the part of the input between the previous match and the current match. The method can be used in conjunction with find() and appendTail(StringBuffer) to walk through the input and replace all occurrences of the Pattern with something else.
      Parameters:
      buffer - the StringBuffer to append to.
      replacement - the replacement text.
      Returns:
      the Matcher itself.
      Throws:
      IllegalStateException - if no successful match has been made.

    • reset

      public Matcher reset()
      Resets the Matcher. This results in the region being set to the whole input. Results of a previous find get lost. The next attempt to find an occurrence of the Pattern in the string will start at the beginning of the input.
      Returns:
      the Matcher itself.

    • reset

      public Matcher reset​(CharSequence input)
      Provides a new input and resets the Matcher. This results in the region being set to the whole input. Results of a previous find get lost. The next attempt to find an occurrence of the Pattern in the string will start at the beginning of the input.
      Parameters:
      input - the new input sequence.
      Returns:
      the Matcher itself.

    • usePattern

      public Matcher usePattern​(Pattern pattern)
      Sets a new pattern for the Matcher. Results of a previous find get lost. The next attempt to find an occurrence of the Pattern in the string will start at the beginning of the input.
      Parameters:
      pattern - the new Pattern.
      Returns:
      the Matcher itself.

    • region

      public Matcher region​(int start, int end)
      Resets this matcher and sets a region. Only characters inside the region are considered for a match.
      Parameters:
      start - the first character of the region.
      end - the first character after the end of the region.
      Returns:
      the Matcher itself.

    • appendTail

      public StringBuffer appendTail​(StringBuffer buffer)
      Appends the (unmatched) remainder of the input to the given StringBuffer. The method can be used in conjunction with find() and appendReplacement(StringBuffer, String) to walk through the input and replace all matches of the Pattern with something else.
      Parameters:
      buffer - the StringBuffer to append to.
      Returns:
      the StringBuffer.
      Throws:
      IllegalStateException - if no successful match has been made.

    • replaceFirst

      public String replaceFirst​(String replacement)
      Replaces the first occurrence of this matcher's pattern in the input with a given string.
      Parameters:
      replacement - the replacement text.
      Returns:
      the modified input string.

    • replaceAll

      public String replaceAll​(String replacement)
      Replaces all occurrences of this matcher's pattern in the input with a given string.
      Parameters:
      replacement - the replacement text.
      Returns:
      the modified input string.

    • pattern

      public Pattern pattern()
      Returns the Pattern instance used inside this matcher.
      Returns:
      the Pattern instance.

    • group

      public String group​(int group)
      Returns the text that matched a given group of the regular expression. Explicit capturing groups in the pattern are numbered left to right in order of their opening parenthesis, starting at 1. The special group 0 represents the entire match (as if the entire pattern is surrounded by an implicit capturing group). For example, "a((b)c)" matching "abc" would give the following groups: 
       0 "abc"
 1 "bc"
 2 "b"

      An optional capturing group that failed to match as part of an overall successful match (for example, "a(b)?c" matching "ac") returns null. A capturing group that matched the empty string (for example, "a(b?)c" matching "ac") returns the empty string.

      Specified by:
      group in interface MatchResult
      Parameters:
      group - the group, ranging from 0 to groupCount() - 1, with 0 representing the whole pattern.
      Returns:
      the text that matched the group.
      Throws:
      IllegalStateException - if no successful match has been made.

    • group

      public String group()
      Returns the text that matched the whole regular expression.
      Specified by:
      group in interface MatchResult
      Returns:
      the text.
      Throws:
      IllegalStateException - if no successful match has been made.

    • find

      public boolean find​(int start)
      Returns true if there is another match in the input, starting from the given position. The region is ignored.
      Throws:
      IndexOutOfBoundsException - if start < 0 || start > input.length()

    • find

      public boolean find()
      Returns the next occurrence of the Pattern in the input. If a previous match was successful, the method continues the search from the first character following that match in the input. Otherwise it searches either from the region start (if one has been set), or from position 0.
      Returns:
      true if (and only if) a match has been found.

    • lookingAt

      public boolean lookingAt()
      Tries to match the Pattern, starting from the beginning of the region (or the beginning of the input, if no region has been set). Doesn't require the Pattern to match against the whole region.
      Returns:
      true if (and only if) the Pattern matches.

    • matches

      public boolean matches()
      Tries to match the Pattern against the entire region (or the entire input, if no region has been set).
      Returns:
      true if (and only if) the Pattern matches the entire region.

    • start

      public int start​(int group) throws IllegalStateException
      Returns the index of the first character of the text that matched a given group.
      Specified by:
      start in interface MatchResult
      Parameters:
      group - the group, ranging from 0 to groupCount() - 1, with 0 representing the whole pattern.
      Returns:
      the character index.
      Throws:
      IllegalStateException - if no successful match has been made.

    • end

      public int end​(int group)
      Returns the index of the first character following the text that matched a given group.
      Specified by:
      end in interface MatchResult
      Parameters:
      group - the group, ranging from 0 to groupCount() - 1, with 0 representing the whole pattern.
      Returns:
      the character index.
      Throws:
      IllegalStateException - if no successful match has been made.

    • quoteReplacement

      public static String quoteReplacement​(String s)
      Returns a replacement string for the given one that has all backslashes and dollar signs escaped.
      Parameters:
      s - the input string.
      Returns:
      the input string, with all backslashes and dollar signs having been escaped.

    • start

      public int start()
      Returns the index of the first character of the text that matched the whole regular expression.
      Specified by:
      start in interface MatchResult
      Returns:
      the character index.
      Throws:
      IllegalStateException - if no successful match has been made.

    • groupCount

      public int groupCount()
      Returns the number of groups in the results, which is always equal to the number of groups in the original regular expression.
      Specified by:
      groupCount in interface MatchResult
      Returns:
      the number of groups.

    • end

      public int end()
      Returns the index of the first character following the text that matched the whole regular expression.
      Specified by:
      end in interface MatchResult
      Returns:
      the character index.
      Throws:
      IllegalStateException - if no successful match has been made.

    • toMatchResult

      public MatchResult toMatchResult()
      Converts the current match into a separate MatchResult instance that is independent from this matcher. The new object is unaffected when the state of this matcher changes.
      Returns:
      the new MatchResult.
      Throws:
      IllegalStateException - if no successful match has been made.

    • useAnchoringBounds

      public Matcher useAnchoringBounds​(boolean value)
      Determines whether this matcher has anchoring bounds enabled or not. When anchoring bounds are enabled, the start and end of the input match the '^' and '$' meta-characters, otherwise not. Anchoring bounds are enabled by default.
      Parameters:
      value - the new value for anchoring bounds.
      Returns:
      the Matcher itself.

    • hasAnchoringBounds

      public boolean hasAnchoringBounds()
      Returns true if this matcher has anchoring bounds enabled. When anchoring bounds are enabled, the start and end of the input match the '^' and '$' meta-characters, otherwise not. Anchoring bounds are enabled by default.

    • useTransparentBounds

      public Matcher useTransparentBounds​(boolean value)
      Determines whether this matcher has transparent bounds enabled or not. When transparent bounds are enabled, the parts of the input outside the region are subject to lookahead and lookbehind, otherwise they are not. Transparent bounds are disabled by default.
      Parameters:
      value - the new value for transparent bounds.
      Returns:
      the Matcher itself.

    • hasTransparentBounds

      public boolean hasTransparentBounds()
      Returns true if this matcher has transparent bounds enabled. When transparent bounds are enabled, the parts of the input outside the region are subject to lookahead and lookbehind, otherwise they are not. Transparent bounds are disabled by default.

    • regionStart

      public int regionStart()
      Returns this matcher's region start, that is, the index of the first character that is considered for a match.

    • regionEnd

      public int regionEnd()
      Returns this matcher's region end, that is, the index of the first character that is not considered for a match.

    • requireEnd

      public boolean requireEnd()
      Returns true if the most recent match succeeded and additional input could cause it to fail. If this method returns false and a match was found, then more input might change the match but the match won't be lost. If a match was not found, then requireEnd has no meaning.

    • hitEnd

      public boolean hitEnd()
      Returns true if the most recent matching operation attempted to access additional text beyond the available input, meaning that additional input could change the results of the match.

    • finalize

      protected void finalize() throws Throwable
      Description copied from class: Object
      Invoked when the garbage collector has detected that this instance is no longer reachable. The default implementation does nothing, but this method can be overridden to free resources.

      Note that objects that override finalize are significantly more expensive than objects that don't. Finalizers may be run a long time after the object is no longer reachable, depending on memory pressure, so it's a bad idea to rely on them for cleanup. Note also that finalizers are run on a single VM-wide finalizer thread, so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary for a class that has a native peer and needs to call a native method to destroy that peer. Even then, it's better to provide an explicit close method (and implement Closeable), and insist that callers manually dispose of instances. This works well for something like files, but less well for something like a BigInteger where typical calling code would have to deal with lots of temporaries. Unfortunately, code that creates lots of temporaries is the worst kind of code from the point of view of the single finalizer thread.

      If you must use finalizers, consider at least providing your own ReferenceQueue and having your own thread process that queue.

      Unlike constructors, finalizers are not automatically chained. You are responsible for calling super.finalize() yourself.

      Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.

      Overrides:
      finalize in class Object
      Throws:
      Throwable

    • toString

      public String toString()
      Returns a string representing this Matcher. The format of this string is unspecified.
      Overrides:
      toString in class Object
      Returns:
      a printable representation of this object.