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What is a Java Lambda Expression?

Java Lambda Expressions are particular code segments that behave like a regular method. They are designed to accept a set of parameters as input and return a value as an output. Unlike methods, a Lambda Expression does not mandatorily require a specific name.

Why Do We Need a Lambda Expression?

The three primary reasons why we need Java Lambda expressions are as follows:

• Lambda converts the code segment into an argument
• It is a method that can be created without instantiating a class
• Lambda can be treated as an Object

Java Lambda Expression Syntax:

(argument-list) -> {body}  

Java lambda expression is consisted of three components.

1) Argument-list: 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.

No Parameter Syntax:

() -> {  
//Body of no parameter lambda  
}  

One Parameter Syntax:

(p1) -> {  
//Body of single parameter lambda  
}  

Two Parameter Syntax:

(p1,p2) -> {  
//Body of multiple parameter lambda  
}  

Functional Interface:

Lambda expression provides implementation of functional interface. An interface which has only one abstract method is called functional interface. Java provides an anotation @FunctionalInterface, which is used to declare an interface as functional interface.

Java Lambda Expression vs Regular Method in Java:

Reference:

https://www.simplilearn.com/tutorials/java-tutorial/java-lambda-expression

https://www.geeksforgeeks.org/lambda-expressions-java-8/

https://www.w3schools.com/java/java_lambda.asp

https://www.javatpoint.com/java-lambda-expressions