Java-Use Logical Operators

Use Logical Operators

You can use the && operator to combine classes that define sets of characters. This is particularly useful when you use it combined with the negation operator(^). For example, if you want to specify that any uppercase consonant is acceptable, you could write the expression that matches this as “[A-CG-IM-Z]{2}”.

However, this can much more conveniently be expressed as “[A-Z&&[^D-FJ-L]]{2}”.

The pattern “[A-Z&&[^D-FJ-L]]{2}” produces the intersection (in other words, the characters common to both sets) of the set of characters “A” through “Z” with the set that is not a uppercase characters D,E,F,J,K and L. To put it another way, the uppercase characters D,E,F,J,K and L are subtracted from the set “A” through “Z” so you are left with just the uppercase consonants.

Program

import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class Javaapp {
  
    public static void main(String[] args) {
        
        Pattern pat = Pattern.compile("[A-Z&&[^D-FJ-L]]{2}");
        Matcher mat = pat.matcher("AABBCCDDEEFFGGHHIIJJKK");
        
        int i = 0;
        while(mat.find())
        {
            i++;
            System.out.println(i+"th subsequence  : "+mat.group());
        }
    }
}