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:
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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.
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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 GeeksforGeeks, 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);
}
} |
Number of vowels in 'Hello GeeksforGeeks, 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 GeeksforGeeks, 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);
}
} |
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 GeeksforGeeks1287 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);
}
} |
Original String : 12345Hello GeeksforGeeks1287 What's 9886up After digit removal : Hello GeeksforGeeks What's up
Reference: Google Guava