Java 8 Lambda Expressions | Code Factory

Lambda expression is a new and important feature of Java which was included in Java SE 8. Lambda expression facilitates functional programming, and simplifies the development a lot.

Syntax

(Arguments / parameters) -> {Body}

Java lambda expression is consisted of three components.

1) Argument / Parameters: It can be empty or non-empty as well.

2) Arrow-token: It is used to link arguments-list and body of expression.

3) Body: It contains expressions and statements for lambda expression.

---

Java Example without Lambda Expression

interface Drawable { public void draw(); } public class Main { public static void main(String[] args) { int width = 10; // without lambda, Drawable implementation using anonymous class Drawable d = new Drawable() { public void draw() { System.out.println("Drawing " + width); } }; d.draw(); } }

Output : 
Drawing 10

---

Java Example with Lambda Expression

@FunctionalInterface // It is optional interface Drawable { public void draw(); } public class Main { public static void main(String[] args) { int width = 10; // with lambda Drawable d2 = () -> { System.out.println("Drawing " + width); }; d2.draw(); } }

Output : 
Drawing 10

---

Java Lambda Expression Example: No Parameter

interface Sayable { public String say(); } public class Main { public static void main(String[] args) { Sayable s = () -> { return "I have nothing to say."; }; System.out.println(s.say()); } }

Output : 
I have nothing to say.

---

Java Lambda Expression Example: Single Parameter

interface Sayable { public String say(String name); } public class Main { public static void main(String[] args) { // Lambda expression with single parameter. Sayable s1 = (name) -> { return "Hello, " + name; }; System.out.println(s1.say("Code")); // You can omit function parentheses Sayable s2 = name -> { return "Hello, " + name; }; System.out.println(s2.say("Factory")); } }

Output : 
Hello, Code Hello, Factory

---

Java Lambda Expression Example: Multiple Parameters

interface Addable { int add(int a, int b); } public class Main { public static void main(String[] args) { // Multiple parameters in lambda expression Addable ad1 = (a, b) -> (a + b); System.out.println(ad1.add(10, 20)); // Multiple parameters with data type in lambda expression Addable ad2 = (int a, int b) -> (a + b); System.out.println(ad2.add(100, 200)); } }

Output : 
30 300

---

Java Lambda Expression Example: Foreach Loop

public class Main { public static void main(String[] args) { List<string> list = new ArrayList<string>(); list.add("Code"); list.add("Factory"); list.forEach((n) -> System.out.println(n)); } }

Output : 
Code Factory




Tags :

Java Tutorials
Java 8 Lambda Expressions
java lambda foreach
Java8 Lambda Expressions
Lambda Expressions
Java Lambda essentials
Lambda expressions in Java