HelloLambda

import java.util.ArrayList;
import java.util.Arrays;

/**
 *
 * @author uttesh.blogspot.com
 */
public class HelloLambda {

    public static void main(String[] args) {
        Arrays.asList("a", "b", "d").forEach(e -> System.out.println(e));
        Arrays.asList("a", "b", "d").forEach((String e) -> System.out.println(e));
        Arrays.asList("a", "b", "d").forEach(e -> {
            System.out.print(e);
        });

        String separator = ",";
        Arrays.asList("a", "b", "d").forEach(
                (String e) -> System.out.print(e + separator));

        Arrays.asList("a", "b", "d").sort((e1, e2) -> {
            int result = e1.compareTo(e2);
            return result;
        });
    }

}

LambdaComparatorSample

import com.uttesh.lambda.model.Person;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

/**
 *
 * @author uttesh.blogspot.com
 */
public class LambdaComparatorSample {

    public static void main(String[] args) {
        List<Person> list = Person.populate();
     //traditional comparator sort 
        traditionComparatorSort(list);
    // Use Lambda instead
        lambdaSort(list);
    }

    public static void traditionComparatorSort(List<Person> list) {
        // Sort with Inner Class
        Collections.sort(list, new Comparator<Person>() {
            public int compare(Person p1, Person p2) {
                return p1.getName().compareTo(p2.getName());
            }
        });
        System.out.println("=== Sorted Asc Name by traditional comparator ===");
        for (Person p : list) {
            System.out.println(" person name :" + p.getName());
        }

    }

    public static void lambdaSort(List<Person> list) {
        Collections.sort(list, (Person p1, Person p2) -> p1.getName().compareTo(p2.getName()));
        System.out.println("=== Sorted Asc Name by lambdaSort ===");
        for (Person p : list) {
            System.out.println(" person name :" + p.getName());
        }

    }
}

Person

import java.time.LocalDate;
import java.time.chrono.IsoChronology;
import java.util.ArrayList;
import java.util.List;

/**
 *
 * @author uttesh.blogspot.com
 */
public class Person {
    public enum Sex {
        MALE, FEMALE
    }
  
    String name; 
    LocalDate birthday;
    Sex gender;
    String emailAddress;
  
    Person(String nameArg, LocalDate birthdayArg,
        Sex genderArg, String emailArg) {
        name = nameArg;
        birthday = birthdayArg;
        gender = genderArg;
        emailAddress = emailArg;
    }  

    public int getAge() {
        return birthday
            .until(IsoChronology.INSTANCE.dateNow())
            .getYears();
    }

    public void printPerson() {
      System.out.println(name + ", " + this.getAge());
    }
    
    public Sex getGender() {
        return gender;
    }
    
    public String getName() {
        return name;
    }
    
    public String getEmailAddress() {
        return emailAddress;
    }
    
    public LocalDate getBirthday() {
        return birthday;
    }
    
    public static int compareByAge(Person a, Person b) {
        return a.birthday.compareTo(b.birthday);
    }

    public static List<Person> populate() {
        
        List<Person> roster = new ArrayList<>();
        roster.add(
            new Person(
            "Uttesh",
            IsoChronology.INSTANCE.date(1984, 12, 20),
            Person.Sex.MALE,
            "uttesh.kumar@gmail.com"));
        roster.add(
            new Person(
            "Sonali",
            IsoChronology.INSTANCE.date(1990, 7, 15),
            Person.Sex.FEMALE, "sonali@example.com"));
        roster.add(
            new Person(
            "Raghu",
            IsoChronology.INSTANCE.date(1991, 8, 13),
            Person.Sex.MALE, "raghu@example.com"));
        roster.add(
            new Person(
            "Yallanki",
            IsoChronology.INSTANCE.date(2000, 9, 12),
            Person.Sex.MALE, "Yallanki@example.com"));
        
        return roster;
    }
}