CharMatcher determines a true or false value for any Java char value. This class provides various methods to handle various Java types for char values.
Declaration: The declaration for com.google.common.base.CharMatcher is as:
@GwtCompatible(emulated = true) public final class CharMatcher extends Object
There are 2 ways to obtain CharMatcher instance:
- Using constants: CharMatcher class provides following constants to obtain CharMatcher instance.
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.
- Using methods provided by CharMatcher class: One can get instance of CharMatcher class by using following methods.
Example 1:
// Java code to get number of matching// characters in given sequence// and display them using countIn()    import com.google.common.base.CharMatcher;  class GFG {      // Driver code    public static void main(String args[])    {          // "anyOf" method returns a char matcher        // that matches any character present in        // the given character sequence.        CharMatcher matcher = CharMatcher.anyOf("aeiou");          String str = "Hello Lazyroar, What's up ?";          // "countIn" returns the number of matching        // characters found in a character sequence.        int vowels = matcher.countIn(str);          // To display the number of vowels in        // character sequence        System.out.println("Number of vowels in '"                           + str + "' are "                           + vowels);    }} |
Output:
Number of vowels in 'Hello Lazyroar, What's up ?' are 9
Some other methods of CharMatcher Class are:
Example 2:
// Java code to get the index// of matching character  import com.google.common.base.CharMatcher;  class GFG {      // Driver code    public static void main(String args[])    {          // "anyOf" method returns a char matcher        // that matches any character present in        // the given character sequence.        CharMatcher matcher = CharMatcher.anyOf("aeiou");          String str = "Hello Lazyroar, What's up ?";          // To return the index of first matching        // character in given input sequence.        int firstIndex = matcher.indexIn(str);          // To Return the index of first matching        // character in given input sequence,        // from given starting index.        int nextIndex = matcher.indexIn(str, firstIndex + 1);          // To return the index of the last matching        // character in a character sequence        int lastIndex = matcher.lastIndexIn(str);          System.out.println("First Index is " + firstIndex);        System.out.println("Next Index is " + nextIndex);        System.out.println("Last Index is " + lastIndex);    }} |
Output:
First Index is 1 Next Index is 4 Last Index is 28
Some other methods of CharMatcher Class are:
Example 3:
// Java code to remove all digits // from a given string  import com.google.common.base.CharMatcher;  class GFG {      // Driver code    public static void main(String args[])    {          // Determines whether a character is        // a digit according to Unicode.        CharMatcher matcher = CharMatcher.DIGIT;          String str = "12345Hello Lazyroar1287 What's 9886up";        System.out.println("Original String : " + str);          // To remove all matching characters        // from given string.        String result = matcher.removeFrom(str);          // To display the string which        // doesn't contain digit        System.out.println("After digit removal : " + result);    }} |
Output:
Original String : 12345Hello Lazyroar1287 What's 9886up After digit removal : Hello Lazyroar What's up
Reference: Google Guava
