CharMatcher Class in Java

The CharMatcher class determines a true or false value for any Java char value, just as Predicate does for any Object.

Create the following java program using any editor of your choice in say C:/> Guava.

Example

Following is the GuavaTester.java code −

import com.google.common.base.CharMatcher;
import com.google.common.base.Splitter;
public class GuavaTester {
   public static void main(String args[]) {
      GuavaTester tester = new GuavaTester();
      tester.testCharMatcher();
   }
   private void testCharMatcher() {
      System.out.println(CharMatcher.DIGIT.retainFrom("mahesh123")); // only the digits
      System.out.println(CharMatcher.WHITESPACE.trimAndCollapseFrom(" Mahesh Parashar ", ' '));
      // trim whitespace at ends, and replace/collapse whitespace into single spaces
      System.out.println(CharMatcher.JAVA_DIGIT.replaceFrom("mahesh123", "*"));
      // star out all digits                  
      System.out.println(CharMatcher.JAVA_DIGIT.or(CharMatcher.JAVA_LOWER_CASE).retainFrom("mahesh123"));
      // eliminate all characters that aren't digits or lowercase
   }
}

Compile the class using javac compiler as follows

C:\Guava>javac GuavaTester.java

Now run the GuavaTester to see the result −

C:\Guava>java GuavaTester

Output

This will produce the following output −

123
Mahesh Parashar
mahesh***
mahesh123