import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; public class JLEComparatorExample { public static void main(String[] args) { List<Person> listOfPerson = new ArrayList<Person>(); listOfPerson.add(new Person("abc", 27)); listOfPerson.add(new Person("mno", 26)); listOfPerson.add(new Person("pqr", 28)); listOfPerson.add(new Person("xyz", 27)); // Without lambda expression. // Sort list by age Comparator<Person> comparator = new Comparator<Person>() { @Override public int compare(Person o1, Person o2) { return o1.getAge() - o2.getAge(); } }; Collections.sort(listOfPerson, comparator); System.out.println(" sort persons by age in ascending order"); for (Person person : listOfPerson) { System.out.println(" Person name : " + person.getName()); } // Witht lambda expression. // Sort list by age Collections.sort(listOfPerson, (Person o1, Person o2) -> { return o1.getAge() - o2.getAge(); }); // Use forEach method added in java 8 System.out.println(" sort persons by age in ascending order"); listOfPerson.forEach( (person) -> System.out.println(" Person name : " + person.getName())); } } class Person { private String name; private int age; public Person(String name, int age) { super(); this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } }