CharMatcher (Guava: Google Core Libraries for Java 16.0 API)

java.lang.Object
- com.google.common.base.CharMatcher

All Implemented Interfaces:

Predicate<Character>
```
@Beta
@GwtCompatible(emulated=true)
public abstract class CharMatcher
extends Object
implements Predicate<Character>
```
Determines a true or false value for any Java char value, just as Predicate does for any Object. Also offers basic text processing methods based on this function. Implementations are strongly encouraged to be side-effect-free and immutable.
Throughout the documentation of this class, the phrase "matching character" is used to mean "any character c for which this.matches(c) returns true".
Note: This class deals only with char values; it does not understand supplementary Unicode code points in the range 0x10000 to 0x10FFFF. Such logical characters are encoded into a String using surrogate pairs, and a CharMatcher treats these just as two separate characters.
Example usages:
```
   String trimmed = WHITESPACE.trimFrom(userInput);
   if (ASCII.matchesAllOf(s)) { ... }
```
See the Guava User Guide article on CharMatcher.
Since:

1.0

Author:

Kevin Bourrillion

Field Summary

Fields
Modifier and Type	Field and Description
`static CharMatcher`	`ANY` Matches any character.
`static CharMatcher`	`ASCII` Determines whether a character is ASCII, meaning that its code point is less than 128.
`static CharMatcher`	`BREAKING_WHITESPACE` Determines whether a character is a breaking whitespace (that is, a whitespace which can be interpreted as a break between words for formatting purposes).
`static CharMatcher`	`DIGIT` Determines whether a character is a digit according to Unicode.
`static CharMatcher`	`INVISIBLE` Determines whether a character is invisible; that is, if its Unicode category is any of SPACE_SEPARATOR, LINE_SEPARATOR, PARAGRAPH_SEPARATOR, CONTROL, FORMAT, SURROGATE, and PRIVATE_USE according to ICU4J.
`static CharMatcher`	`JAVA_DIGIT` Determines whether a character is a digit according to `Java's definition`.
`static CharMatcher`	`JAVA_ISO_CONTROL` Determines whether a character is an ISO control character as specified by `Character.isISOControl(char)`.
`static CharMatcher`	`JAVA_LETTER` Determines whether a character is a letter according to `Java's definition`.
`static CharMatcher`	`JAVA_LETTER_OR_DIGIT` Determines whether a character is a letter or digit according to `Java's definition`.
`static CharMatcher`	`JAVA_LOWER_CASE` Determines whether a character is lower case according to `Java's definition`.
`static CharMatcher`	`JAVA_UPPER_CASE` Determines whether a character is upper case according to `Java's definition`.
`static CharMatcher`	`NONE` Matches no characters.
`static CharMatcher`	`SINGLE_WIDTH` Determines whether a character is single-width (not double-width).
`static CharMatcher`	`WHITESPACE` Determines whether a character is whitespace according to the latest Unicode standard, as illustrated here.

Constructor Summary

Constructors
Modifier Constructor and Description

protected CharMatcher()
Constructor for use by subclasses.

Constructors
Modifier	Constructor and Description
`protected`	`CharMatcher()` Constructor for use by subclasses.

Method Summary

Methods
Modifier and Type	Method and Description
`CharMatcher`	`and(CharMatcher other)` Returns a matcher that matches any character matched by both this matcher and `other`.
`static CharMatcher`	`anyOf(CharSequence sequence)` Returns a `char` matcher that matches any character present in the given character sequence.
`boolean`	`apply(Character character)` Deprecated. Provided only to satisfy the `Predicate` interface; use `matches(char)` instead.
`String`	`collapseFrom(CharSequence sequence, char replacement)` Returns a string copy of the input character sequence, with each group of consecutive characters that match this matcher replaced by a single replacement character.
`int`	`countIn(CharSequence sequence)` Returns the number of matching characters found in a character sequence.
`static CharMatcher`	`forPredicate(Predicate<? super Character> predicate)` Returns a matcher with identical behavior to the given `Character`-based predicate, but which operates on primitive `char` instances instead.
`int`	`indexIn(CharSequence sequence)` Returns the index of the first matching character in a character sequence, or `-1` if no matching character is present.
`int`	`indexIn(CharSequence sequence, int start)` Returns the index of the first matching character in a character sequence, starting from a given position, or `-1` if no character matches after that position.
`static CharMatcher`	`inRange(char startInclusive, char endInclusive)` Returns a `char` matcher that matches any character in a given range (both endpoints are inclusive).
`static CharMatcher`	`is(char match)` Returns a `char` matcher that matches only one specified character.
`static CharMatcher`	`isNot(char match)` Returns a `char` matcher that matches any character except the one specified.
`int`	`lastIndexIn(CharSequence sequence)` Returns the index of the last matching character in a character sequence, or `-1` if no matching character is present.
`abstract boolean`	`matches(char c)` Determines a true or false value for the given character.
`boolean`	`matchesAllOf(CharSequence sequence)` Returns `true` if a character sequence contains only matching characters.
`boolean`	`matchesAnyOf(CharSequence sequence)` Returns `true` if a character sequence contains at least one matching character.
`boolean`	`matchesNoneOf(CharSequence sequence)` Returns `true` if a character sequence contains no matching characters.
`CharMatcher`	`negate()` Returns a matcher that matches any character not matched by this matcher.
`static CharMatcher`	`noneOf(CharSequence sequence)` Returns a `char` matcher that matches any character not present in the given character sequence.
`CharMatcher`	`or(CharMatcher other)` Returns a matcher that matches any character matched by either this matcher or `other`.
`CharMatcher`	`precomputed()` Returns a `char` matcher functionally equivalent to this one, but which may be faster to query than the original; your mileage may vary.
`String`	`removeFrom(CharSequence sequence)` Returns a string containing all non-matching characters of a character sequence, in order.
`String`	`replaceFrom(CharSequence sequence, char replacement)` Returns a string copy of the input character sequence, with each character that matches this matcher replaced by a given replacement character.
`String`	`replaceFrom(CharSequence sequence, CharSequence replacement)` Returns a string copy of the input character sequence, with each character that matches this matcher replaced by a given replacement sequence.
`String`	`retainFrom(CharSequence sequence)` Returns a string containing all matching characters of a character sequence, in order.
`String`	`toString()` Returns a string representation of this `CharMatcher`, such as `CharMatcher.or(WHITESPACE, JAVA_DIGIT)`.
`String`	`trimAndCollapseFrom(CharSequence sequence, char replacement)` Collapses groups of matching characters exactly as `collapseFrom(java.lang.CharSequence, char)` does, except that groups of matching characters at the start or end of the sequence are removed without replacement.
`String`	`trimFrom(CharSequence sequence)` Returns a substring of the input character sequence that omits all characters this matcher matches from the beginning and from the end of the string.
`String`	`trimLeadingFrom(CharSequence sequence)` Returns a substring of the input character sequence that omits all characters this matcher matches from the beginning of the string.
`String`	`trimTrailingFrom(CharSequence sequence)` Returns a substring of the input character sequence that omits all characters this matcher matches from the end of the string.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.google.common.base.Predicate
equals

- Field Detail
  - BREAKING_WHITESPACE
```
public static final CharMatcher BREAKING_WHITESPACE
```
    Determines whether a character is a breaking whitespace (that is, a whitespace which can be interpreted as a break between words for formatting purposes). See WHITESPACE for a discussion of that term.
    
    Since:
    
    2.0
  - ASCII
```
public static final CharMatcher ASCII
```
    Determines whether a character is ASCII, meaning that its code point is less than 128.
  - DIGIT
```
public static final CharMatcher DIGIT
```
    Determines whether a character is a digit according to Unicode. If you only care to match ASCII digits, you can use inRange('0', '9').
  - JAVA_DIGIT
```
public static final CharMatcher JAVA_DIGIT
```
    Determines whether a character is a digit according to Java's definition. If you only care to match ASCII digits, you can use inRange('0', '9').
  - JAVA_LETTER
```
public static final CharMatcher JAVA_LETTER
```
    Determines whether a character is a letter according to Java's definition. If you only care to match letters of the Latin alphabet, you can use inRange('a', 'z').or(inRange('A', 'Z')).
  - JAVA_LETTER_OR_DIGIT
```
public static final CharMatcher JAVA_LETTER_OR_DIGIT
```
    Determines whether a character is a letter or digit according to Java's definition.
  - JAVA_UPPER_CASE
```
public static final CharMatcher JAVA_UPPER_CASE
```
    Determines whether a character is upper case according to Java's definition.
  - JAVA_LOWER_CASE
```
public static final CharMatcher JAVA_LOWER_CASE
```
    Determines whether a character is lower case according to Java's definition.
  - JAVA_ISO_CONTROL
```
public static final CharMatcher JAVA_ISO_CONTROL
```
    Determines whether a character is an ISO control character as specified by Character.isISOControl(char).
  - INVISIBLE
```
public static final CharMatcher INVISIBLE
```
    Determines whether a character is invisible; that is, if its Unicode category is any of SPACE_SEPARATOR, LINE_SEPARATOR, PARAGRAPH_SEPARATOR, CONTROL, FORMAT, SURROGATE, and PRIVATE_USE according to ICU4J.
  - SINGLE_WIDTH
```
public static final CharMatcher SINGLE_WIDTH
```
    Determines whether a character is single-width (not double-width). When in doubt, this matcher errs on the side of returning false (that is, it tends to assume a character is double-width).
    Note: as the reference file evolves, we will modify this constant to keep it up to date.
  - ANY
```
public static final CharMatcher ANY
```
    Matches any character.
  - NONE
```
public static final CharMatcher NONE
```
    Matches no characters.
  - WHITESPACE
```
public static final CharMatcher WHITESPACE
```
    Determines whether a character is whitespace according to the latest Unicode standard, as illustrated here. This is not the same definition used by other Java APIs. (See a comparison of several definitions of "whitespace".)
    Note: as the Unicode definition evolves, we will modify this constant to keep it up to date.
- Constructor Detail
  - CharMatcher
```
protected CharMatcher()
```
    Constructor for use by subclasses. When subclassing, you may want to override toString() to provide a useful description.
- Method Detail
  - is
```
public static CharMatcher is(char match)
```
    Returns a char matcher that matches only one specified character.
  - isNot
```
public static CharMatcher isNot(char match)
```
    Returns a char matcher that matches any character except the one specified.
    To negate another CharMatcher, use negate().
  - anyOf
```
public static CharMatcher anyOf(CharSequence sequence)
```
    Returns a char matcher that matches any character present in the given character sequence.
  - noneOf
```
public static CharMatcher noneOf(CharSequence sequence)
```
    Returns a char matcher that matches any character not present in the given character sequence.
  - inRange
```
public static CharMatcher inRange(char startInclusive,
                  char endInclusive)
```
    Returns a char matcher that matches any character in a given range (both endpoints are inclusive). For example, to match any lowercase letter of the English alphabet, use CharMatcher.inRange('a', 'z').
    
    Throws:
    
    IllegalArgumentException - if endInclusive < startInclusive
  - forPredicate
```
public static CharMatcher forPredicate(Predicate<? super Character> predicate)
```
    Returns a matcher with identical behavior to the given Character-based predicate, but which operates on primitive char instances instead.
  - matches
```
public abstract boolean matches(char c)
```
    Determines a true or false value for the given character.
  - negate
```
public CharMatcher negate()
```
    Returns a matcher that matches any character not matched by this matcher.
  - and
```
public CharMatcher and(CharMatcher other)
```
    Returns a matcher that matches any character matched by both this matcher and other.
  - or
```
public CharMatcher or(CharMatcher other)
```
    Returns a matcher that matches any character matched by either this matcher or other.
  - precomputed
```
public CharMatcher precomputed()
```
    Returns a char matcher functionally equivalent to this one, but which may be faster to query than the original; your mileage may vary. Precomputation takes time and is likely to be worthwhile only if the precomputed matcher is queried many thousands of times.
    This method has no effect (returns this) when called in GWT: it's unclear whether a precomputed matcher is faster, but it certainly consumes more memory, which doesn't seem like a worthwhile tradeoff in a browser.
  - matchesAnyOf
```
public boolean matchesAnyOf(CharSequence sequence)
```
    Returns true if a character sequence contains at least one matching character. Equivalent to !matchesNoneOf(sequence).
    The default implementation iterates over the sequence, invoking matches(char) for each character, until this returns true or the end is reached.
    
    Parameters:
    sequence - the character sequence to examine, possibly empty
    
    Returns:
    true if this matcher matches at least one character in the sequence
    Since:
    
    8.0
  - matchesAllOf
```
public boolean matchesAllOf(CharSequence sequence)
```
    Returns true if a character sequence contains only matching characters.
    The default implementation iterates over the sequence, invoking matches(char) for each character, until this returns false or the end is reached.
    
    Parameters:
    sequence - the character sequence to examine, possibly empty
    
    Returns:
    true if this matcher matches every character in the sequence, including when the sequence is empty
  - matchesNoneOf
```
public boolean matchesNoneOf(CharSequence sequence)
```
    Returns true if a character sequence contains no matching characters. Equivalent to !matchesAnyOf(sequence).
    The default implementation iterates over the sequence, invoking matches(char) for each character, until this returns false or the end is reached.
    
    Parameters:
    sequence - the character sequence to examine, possibly empty
    
    Returns:
    true if this matcher matches every character in the sequence, including when the sequence is empty
  - indexIn
```
public int indexIn(CharSequence sequence)
```
    Returns the index of the first matching character in a character sequence, or -1 if no matching character is present.
    The default implementation iterates over the sequence in forward order calling matches(char) for each character.
    
    Parameters:
    sequence - the character sequence to examine from the beginning
    
    Returns:
    an index, or -1 if no character matches
  - indexIn
```
public int indexIn(CharSequence sequence,
          int start)
```
    Returns the index of the first matching character in a character sequence, starting from a given position, or -1 if no character matches after that position.
    The default implementation iterates over the sequence in forward order, beginning at start, calling matches(char) for each character.
    
    Parameters:
    sequence - the character sequence to examine
    start - the first index to examine; must be nonnegative and no greater than sequence.length()
    
    Returns:
    the index of the first matching character, guaranteed to be no less than start, or -1 if no character matches
    
    Throws:
    
    IndexOutOfBoundsException - if start is negative or greater than sequence.length()
  - lastIndexIn
```
public int lastIndexIn(CharSequence sequence)
```
    Returns the index of the last matching character in a character sequence, or -1 if no matching character is present.
    The default implementation iterates over the sequence in reverse order calling matches(char) for each character.
    
    Parameters:
    sequence - the character sequence to examine from the end
    
    Returns:
    an index, or -1 if no character matches
  - countIn
```
public int countIn(CharSequence sequence)
```
    Returns the number of matching characters found in a character sequence.
  - removeFrom
```
@CheckReturnValue
public String removeFrom(CharSequence sequence)
```
    Returns a string containing all non-matching characters of a character sequence, in order. For example:
```
   CharMatcher.is('a').removeFrom("bazaar")
```
    ... returns "bzr".
  - retainFrom
```
@CheckReturnValue
public String retainFrom(CharSequence sequence)
```
    Returns a string containing all matching characters of a character sequence, in order. For example:
```
   CharMatcher.is('a').retainFrom("bazaar")
```
    ... returns "aaa".
  - replaceFrom
```
@CheckReturnValue
public String replaceFrom(CharSequence sequence,
                                  char replacement)
```
    Returns a string copy of the input character sequence, with each character that matches this matcher replaced by a given replacement character. For example:
```
   CharMatcher.is('a').replaceFrom("radar", 'o')
```
    ... returns "rodor".
    The default implementation uses indexIn(CharSequence) to find the first matching character, then iterates the remainder of the sequence calling matches(char) for each character.
    Parameters:
    sequence - the character sequence to replace matching characters in
    replacement - the character to append to the result string in place of each matching character in sequence
    
    Returns:
    the new string
  - replaceFrom
```
@CheckReturnValue
public String replaceFrom(CharSequence sequence,
                                  CharSequence replacement)
```
    Returns a string copy of the input character sequence, with each character that matches this matcher replaced by a given replacement sequence. For example:
```
   CharMatcher.is('a').replaceFrom("yaha", "oo")
```
    ... returns "yoohoo".
    Note: If the replacement is a fixed string with only one character, you are better off calling replaceFrom(CharSequence, char) directly.
    Parameters:
    sequence - the character sequence to replace matching characters in
    replacement - the characters to append to the result string in place of each matching character in sequence
    
    Returns:
    the new string
  - trimFrom
```
@CheckReturnValue
public String trimFrom(CharSequence sequence)
```
    Returns a substring of the input character sequence that omits all characters this matcher matches from the beginning and from the end of the string. For example:
```
   CharMatcher.anyOf("ab").trimFrom("abacatbab")
```
    ... returns "cat".
    Note that:
```
   CharMatcher.inRange('\0', ' ').trimFrom(str)
```
    ... is equivalent to String.trim().
  - trimLeadingFrom
```
@CheckReturnValue
public String trimLeadingFrom(CharSequence sequence)
```
    Returns a substring of the input character sequence that omits all characters this matcher matches from the beginning of the string. For example:
```
 CharMatcher.anyOf("ab").trimLeadingFrom("abacatbab")
```
    ... returns "catbab".
  - trimTrailingFrom
```
@CheckReturnValue
public String trimTrailingFrom(CharSequence sequence)
```
    Returns a substring of the input character sequence that omits all characters this matcher matches from the end of the string. For example:
```
 CharMatcher.anyOf("ab").trimTrailingFrom("abacatbab")
```
    ... returns "abacat".
  - collapseFrom
```
@CheckReturnValue
public String collapseFrom(CharSequence sequence,
                                   char replacement)
```
    Returns a string copy of the input character sequence, with each group of consecutive characters that match this matcher replaced by a single replacement character. For example:
```
   CharMatcher.anyOf("eko").collapseFrom("bookkeeper", '-')
```
    ... returns "b-p-r".
    The default implementation uses indexIn(CharSequence) to find the first matching character, then iterates the remainder of the sequence calling matches(char) for each character.
    Parameters:
    sequence - the character sequence to replace matching groups of characters in
    replacement - the character to append to the result string in place of each group of matching characters in sequence
    
    Returns:
    the new string
  - trimAndCollapseFrom
```
@CheckReturnValue
public String trimAndCollapseFrom(CharSequence sequence,
                                          char replacement)
```
    Collapses groups of matching characters exactly as collapseFrom(java.lang.CharSequence, char) does, except that groups of matching characters at the start or end of the sequence are removed without replacement.
  - apply
```
@Deprecated
public boolean apply(Character character)
```
    Deprecated. Provided only to satisfy the Predicate interface; use matches(char) instead.
    
    Description copied from interface: Predicate
    Returns the result of applying this predicate to input. This method is generally expected, but not absolutely required, to have the following properties:
    - Its execution does not cause any observable side effects.
    - The computation is consistent with equals; that is, Objects.equal(a, b) implies that predicate.apply(a) == predicate.apply(b)).
    Specified by:
    
    apply in interface Predicate<Character>
  - toString
```
public String toString()
```
    Returns a string representation of this CharMatcher, such as CharMatcher.or(WHITESPACE, JAVA_DIGIT).
    
    Overrides:
    
    toString in class Object
    
    Returns:
    a string representation of the object.

Class CharMatcher

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface com.google.common.base.Predicate

Field Detail

BREAKING_WHITESPACE

ASCII

DIGIT

JAVA_DIGIT

JAVA_LETTER

JAVA_LETTER_OR_DIGIT

JAVA_UPPER_CASE

JAVA_LOWER_CASE

JAVA_ISO_CONTROL

INVISIBLE

SINGLE_WIDTH

ANY

NONE

WHITESPACE

Constructor Detail

CharMatcher

Method Detail

is

isNot

anyOf

noneOf

inRange

forPredicate

matches

negate

and

or

precomputed

matchesAnyOf

matchesAllOf

matchesNoneOf

indexIn

indexIn

lastIndexIn

countIn

removeFrom

retainFrom

replaceFrom

replaceFrom

trimFrom

trimLeadingFrom

trimTrailingFrom

collapseFrom

trimAndCollapseFrom

apply

toString