Lambda Expression Javascript

Michael Zippo 04.11.2021

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How to use lambda expressions in Java

Have you ever thought that some methods could fit on one line, if only there was no Java you would need to use detailed syntax to declare a method? You are not the only one.

Methods are an extremely useful function in programming.

A method is a block of code that does something specific to your program. They are used because once a method is defined it can be called multiple times. This helps to reduce redundancy in your code, which makes it easier to maintain your code.

In this guide, we are going to talk about lambda expressions in Java. This is a special type of method that you can use called a lambda expression, which implements a functional interface. We are going to talk about how they work and why they are used.

What is a functional interface?

Before talking about lambda expressions, you need to understand functional interfaces. These are interfaces that only contain an abstract method. The only abstract method contained in a functional interface indicates the purpose of the interface.

Let’s take this example:.

We’ve created an interface called CalculateThree. This interface has only one method, multiply_by_three, which means it is a functional interface.

What is a Java lambda expression?

A lambda expression is an anonymous process. It is used to implement a method which has been defined within a functional interface. Lambda expressions are sometimes referred to as anonymous methods because they do not have a name

Lambda expressions make use of the arrow operator, which separates them into two sections:

the side left contains the parameters used by the expression; the right side contains the code that will be executed when the Lambda expression is executed. Lambda functions can accept a single parameter or multiple parameters

How to use a lambda expression

Let’s create a program that takes a number entered by a user and multiplies by three. start by writing code that accepts a number from a user:

When we run this code, our user will be asked to enter a number to multiply. Our program will read this number from the "user_number‚" variable. You can learn more about how the Scanner class works by reading our Java Scanner tutorial .

So, let’s go g to define a lambda expression to multiply the number by three. Paste the following code above your main method:

This code defines the interface that our lambda expression will refer to. Then add the following code to the bottom of the main method in the class:

We used the CalculateThree interface to declare a variable called "multiply". This stores the code for our lambda expression. The lambda expression is related to multiply_by_three in our CalculateThree interface because multiply_by_three is the only function in the interface.

We point notation therefore used to call this function:

dot notation lets you specify the name of the class or interface you want to reference, followed by a dot, the name of the method you want to access. In this case, we want to access the multiply_by_three in the "Multiply" Interface

Our last code looks like this:

Let’s run our code and insert the number 3 to multiply:

Our code multiplied with successful e the number we entered by 3. This action was carried out by using the lambda expression that we have defined

How to use an expression lambda block

expressions lambda can appear in two forms:. expressions or using blocks. The lambda block syntax is used when the code on the right side of the arrow spans multiple lines.

Block syntax is where you place code in the right side of a lambda expression with braces. ({})

Let’s take this example:

We have declared a lambda expression called send_greeting. This expression refers to the GreetUser interface that we defined at the start of our program. Our lambda expression does two things. It:

Print "Hello!" at console
Print "Welcome" followed by the username, at console

Since this requires two lines of code, we used syntax block. The code on the right side of our lambda expression is enclosed in braces.

Conclusion

Lambda expressions are anonymous methods that implement a functional interface. These functions are sometimes referred to as classes or anonymous functions because they do not have a name and do not operate on their own

Are you up for a challenge? Write a lambda expression that checks whether a number is same or not. In this case, "X is same" should be printed on the console, where X is the number being tested; otherwise, "X is odd" must be printed on the console.

You are now ready to start working with lambda expressions in Java like an expert!

We hope this article has helped you to resolve the problem. Apart from Lambda Expression Javascript, check other __main__ Python module-related topics.