java.util.regex
Class Matcher

java.lang.Object
  java.util.regex.Matcher

All Implemented Interfaces:

MatchResult

public final class Matcher
extends Object
implements MatchResult

Provides a means of matching regular expressions against a given input, finding occurrences of regular expressions in a given input, or replacing parts of a given input. A Matcher instance has an associated Pattern instance and an input text. A typical use case is to iteratively find all occurrences of the Pattern, until the end of the input is reached, as the following example illustrates:

 Pattern p = Pattern.compile("[A-Za-z]+");
  
 Matcher m = p.matcher("Hello, Android!");
 while (m.find()) {
     System.out.println(m.group()); // prints "Hello" and "Android"
 }
 

The Matcher has a state that results from the previous operations. For example, it knows whether the most recent attempt to find the Pattern was successful and at which position the next attempt would resume the search. Depending on the application's needs, it may become necessary to explicitly reset() this state from time to time.

Since:

Android 1.0

Constructor Summary

Matcher(Pattern pattern, CharSequence input)
Creates a matcher for a given combination of pattern and input.

Method Summary

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() Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
boolean	find() Returns the next occurrence of the Pattern in the input.
boolean	find(int start) Returns the next occurrence of the Pattern in the input.
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() Indicates whether this matcher has anchoring bounds enabled.
boolean	hasTransparentBounds() Indicates whether this matcher has transparent bounds enabled.
boolean	hitEnd() Indicates whether the last match hit the end of the input.
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 first character that is not considered for a match.
int	regionStart() Returns this matcher's region start, that is, 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() Indicates whether more input might change a successful match into an unsuccessful one.
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.
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, toString, wait, wait, wait

Constructor Detail

Matcher

Matcher(Pattern pattern,
        CharSequence input)

Creates a matcher for a given combination of pattern and input. Both elements can be changed later on.

Parameters:

pattern - the pattern to use.

input - the input to use.

Method Detail

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.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

pattern

public Pattern pattern()

Returns the Pattern instance used inside this matcher.

Returns:

the Pattern instance.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

regionStart

public int regionStart()

Returns this matcher's region start, that is, the first character that is considered for a match.

Returns:

the start of the region.

Since:

Android 1.0

regionEnd

public int regionEnd()

Returns this matcher's region end, that is, the first character that is not considered for a match.

Returns:

the end of the region.

Since:

Android 1.0

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.

Since:

Android 1.0

hasAnchoringBounds

public boolean hasAnchoringBounds()

Indicates whether 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.

Returns:

true if (and only if) the Matcher uses anchoring bounds.

Since:

Android 1.0

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.

Since:

Android 1.0

hasTransparentBounds

public boolean hasTransparentBounds()

Indicates whether 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.

Returns:

true if (and only if) the Matcher uses anchoring bounds.

Since:

Android 1.0

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.

Since:

Android 1.0

find

public boolean find(int start)

Returns the next occurrence of the Pattern in the input. The method starts the search from the given character in the input.

Parameters:

start - The index in the input at which the find operation is to begin. If this is less than the start of the region, it is automatically adjusted to that value. If it is beyond the end of the region, the method will fail.

Returns:

true if (and only if) a match has been found.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

start

public int start()
          throws IllegalStateException

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.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

group

public String group(int group)

Returns the text that matched a given group of the regular expression.

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.

Since:

Android 1.0

hitEnd

public boolean hitEnd()

Indicates whether the last match hit the end of the input.

Returns:

true if (and only if) the last match hit the end of the input.

Since:

Android 1.0

requireEnd

public boolean requireEnd()

Indicates whether more input might change a successful match into an unsuccessful one.

Returns:

true if (and only if) more input might change a successful match into an unsuccessful one.

Since:

Android 1.0

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.

Since:

Android 1.0

appendReplacement

public Matcher appendReplacement(StringBuffer buffer,
                                 String replacement)
                          throws IllegalStateException

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.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

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.

Since:

Android 1.0

finalize

protected void finalize()

Description copied from class: Object

Called by the virtual machine when there are no longer any (non-weak) references to the receiver. Subclasses can use this facility to guarantee that any associated resources are cleaned up before the receiver is garbage collected. Uncaught exceptions which are thrown during the running of the method cause it to terminate immediately, but are otherwise ignored.

Note: The virtual machine assumes that the implementation in class Object is empty.

Overrides:

finalize in class Object