lambda

import java.util.*;
import java.util.function.Predicate;

public class Ex1{

    public static void main(String[] args) {

        Set<Character> chars = new HashSet<>();
        chars.add('a');
        chars.add('b');
        chars.add('c');
        chars.add('d');
        String line1 = "abcd";
        String line2 = "qwer";

        Predicate<String> isIllegalString = s -> s.contains(!chars);

        System.out.println(isIllegalString.test(line1));
        System.out.println(isIllegalString.test(line2));

    }

}