What is Lambda Expression In Java ?

Lambda Expression

The biggest new feature of java-8 is Lambda Expression. It simplifies the development a lot means it cut lines of code. The syntax for it is “parameters -> body” , Some important rules to syntax is : 

• Declaring the types of the parameters is optional.
• Using parentheses around the parameter is optional if you have only one parameter.
• Using curly braces is optional (unless you need multiple statements).
• The “return” keyword is optional if you have a single expression that returns a value.

Example Showing Lambda Expression:

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

interface MathOperation{

int operation(int a,int b);

}

public class LambdaExample {

public static void main(String[] args) {

// with variable type declaration

MathOperation add = (int a,int b) -> a+b;

System.out.println("ADDITION\t:"+add.operation(5, 2));

// without variable type declaration

MathOperation sub = (a,b) -> a-b;

System.out.println("SUBSTRACTION\t:"+sub.operation(5, 3));

// with return statement along with curly braces

MathOperation div = (a,b) -> {return a/b ; };

System.out.println("DIVIDE\t\t:"+div.operation(10, 5));

new Thread( () -> System.out.println("In Java8, Lambda expression rocks !!") ).start();

// Traversing Arraylist in one line

List<Integer> l=new ArrayList<Integer>();

for(int i=0;i<10;i++){

l.add(i);

}

l.forEach( n -> System.out.print(n));

// Providing the type of parameter is optional 

l.forEach((Integer n) -> System.out.print(n));

// Sorting Arraylist using Lambda Expression in one line

List<Integer> list = new ArrayList<>();

list.add(2);

list.add(5);

list.add(3);

Collections.sort(list , (i,j) -> i.compareTo(j));

System.out.println("\nSORTED LIST : "+list);

// Traversing Map using Lambda Expression 

Map<String, Integer> items = new HashMap<>();

items.put("A", 10);

items.put("B", 20);

items.put("C", 30);

items.put("D", 40);

items.put("E", 50);

items.put("F", 60);

items.forEach((k,v)->System.out.println(k+":::"+v));

}

}

Program Output :

ADDITION :7

SUBSTRACTION :2

DIVIDE :2

In Java8, Lambda expression rocks !!

01234567890123456789

SORTED LIST : [2, 3, 5]

A:::10

B:::20

C:::30

D:::40

E:::50

F:::60

Blog Author - Pushkar Khosla,
Software Developer by Profession with 3.0 Yrs of Experience , through this blog i'am sharing my industrial Java Knowledge to entire world. For any question or query any one can comment below or mail me at pushkar.itsitm52@gmail.com.

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