Table of Contents. Java 8 Comparator Sorting - Multiple Fields Example using Collections.sort() To sort on a single field then need to use the Comparator.comparing() method from Comparator class.. Sort Without Lambda. You will learn how to use Comparator as lambda expression, method reference, chain multiple comparator with code multiple examples. 7. Sort objects on multiple fields /properties – Comparator interface (lambda stream java 8) Given a list of user defined objects , we would like sort the objects on multiple field or properties. Example 1: Classic Comparator ; Before Java 8, it’s very common that an anonymous class is used to handle click event of a JButton, as shown in the following code. Anonymous class listener. Instead, it is used to implement a method defined by the functional interface.A lambda expression used with any functional interface and Comparator is a functional interface.The Comparator interface has used when sorting a collection of objects compared with each other. The lambda is initialized with its target type as Comparator and Serializable. Object-oriented calculator. Sorting based on multiple fields, you first have to create the two comparators using Comparator.comparing() method and next call Comparator.thenComparing() method.. In this article, we will show you how to work with Java 8 Lambda expressions using the Comparator interface in Java. Java 8 Lambda - Sort List in Ascending and Descending Order | Comparator Example Since Comparator is a functional interface, Java 8 onward Comparator can also be implemented as a lambda expression in Java. The first two inner classes at the top implement a Comparator.The top one is used to sort by last name and the second one sorts by age. With Java-8, we can use Lambda to reduce multiple lines of code to single line. Prior to Java-8, we use anonymous inner class implementation. Comparator as a lambda expression. 1. This way you’re guaranteed that the passed comparator will be serializable. Hot Network Questions Why is gravity considered a negative vector in a pendulum question? We use Comparator to sort list of elements. A lambda expression is an anonymous method and doesn't execute on its own in java. There are 4 methods defined as well: two that handle sorting by age and two that handle sorting by last name. We will use java 8 lambda stream to sort objects. This page gives a simple example of Lambda implementation on Comparator usage. The next two lines of code instantiate a Comparator object that handles sorting with lambda expressions.. Comparator Implementation. Before Java 8 was released, we had to create an anonymous inner class for the Comparator to sort a collection. Take a look at the code snippet below – 2. In the example code there is a Person class with firstName, lastName and age fields. 1. This example shows how to implement an anonymous listener within the scope of Comparator comes with one abstract method called compareTo(). Generic Comparator Using Class Fields & Lambda Java. Note the return type of method is just Comparator , but because Serializable is also inscribed to it while initialization, it can always be serialized even though this message is lost in method signature. In this article you will explore Java Comparator. Lambda – Listener Example. Comparator as lambda expression, java examples. Java 8’s Comparator as an assignment target for LambdaExpressions Given the fact that its a functional interface, an instance of a Comparator can now be created in Java 8 with a lambda expression specifying its comparison logic. Using Lambda expression: The Java 8 equivalent code using Lambda expression would look like this: Comparator sortingByName = (Student s1, Student s2)->s1.getName().compareTo(s2.getName()); Note: In Java 8, the List interface supports the sort() method so you need not to use the Comparator.sort(), instead you can use the List.sort() method.