---
title: "What are lambda expressions in Java? How do they simplify code?"  
description: "Lambda expressions in Java are a feature introduced in Java 8 that provides a clear and concise way to represent instances of single-method interfaces"  
author: "Ravi Vishwakarma"  
published: 2024-07-19  
updated: 2024-07-19  
canonical: https://www.mindstick.com/blog/304513/what-are-lambda-expressions-in-java-how-do-they-simplify-code  
category: "java"  
tags: ["java", "javac"]  
reading_time: 2 minutes  

---

# What are lambda expressions in Java? How do they simplify code?

**Lambda expressions** in Java are a feature introduced in Java 8 that provides a clear and concise way to represent instances of single-method interfaces ([functional interfaces](https://www.mindstick.com/forum/159556/what-are-functional-interfaces-used-for-in-java-8)). They are essentially a shorthand for anonymous classes with a single method.

**Lambda expressions** in Java simplify code by reducing verbosity, improving readability, and enabling more expressive and functional-style programming. They are a powerful feature that enhances the way you write and understand Java code.

## Syntax of Lambda Expressions

The syntax of a lambda expression is:

```plaintext
(parameters) -> expression
or
(parameters) -> { statements; }
```

### Simplifying Code with Lambda Expressions

**Reducing Boilerplate Code:** Before Java 8, implementing an [interface](https://www.mindstick.com/articles/12101/interfaces-in-java-extending-interfaces) with a single method (like `Runnable` or `Comparator`) required an anonymous [inner class](https://www.mindstick.com/articles/12104/nested-classes-in-java-more-with-inner-classes). With lambda expressions, this can be done in a much more concise way.

```java
// Before Java 8
Runnable runnable = new Runnable() {
    @Override
    public void run() {
        System.out.println("Hello, World!");
    }
};

// With Lambda Expression
Runnable runnable = () -> System.out.println("Hello, World!");
```

**Improving Readability:** Lambda expressions make the code more readable and expressive, especially for [operations](https://www.mindstick.com/blog/304985/how-does-devops-bridge-the-gap-between-development-and-operations-teams-like-git) on [collections](https://www.mindstick.com/articles/12458/what-are-collections-in-c-sharp), such as filtering, mapping, and reducing.

```java
// Before Java 8
List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
List<String> filteredNames = new ArrayList<>();
for (String name : names) {
    if (name.startsWith("A")) {
        filteredNames.add(name);
    }
}

// With Lambda Expression and Streams
List<String> filteredNames = names.stream()
                                   .filter(name -> name.startsWith("A"))
                                   .collect(Collectors.toList());
```

**Enabling [Functional Programming](https://www.mindstick.com/forum/23327/why-hasn-t-functional-programming-taken-over-yet):** Lambda expressions enable functional programming [techniques](https://www.mindstick.com/articles/13015/5-practical-tips-and-techniques-to-write-an-essay) in Java. They work seamlessly with the new Stream API introduced in Java 8, allowing for more functional-style operations on collections.

```java
// Java program to illustrate the concept
// of Collection objects storage in a HashSet
import java.io.*;
import java.util.*;

class CollectionObjectStorage {

    public static void main(String[] args)
    {
        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
        int sum = numbers.stream()
                 .filter(n -> n % 2 == 0)
                 .mapToInt(n -> n * n)
                 .sum();
        System.out.println(sum);


        List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
        names.forEach(name -> System.out.println(name));

    }
}

```

## Output:

```plaintext
20
Alice
Bob
Charlie
```

## Read more

[**What are lambda expressions, and how are they used in LINQ queries?**](https://www.mindstick.com/forum/159874/what-are-lambda-expressions-and-how-are-they-used-in-linq-queries)

[**How to use a lambda expression in Enumerable.Distinct()?**](https://www.mindstick.com/forum/159569/how-to-use-a-lambda-expression-in-enumerable-distinct)

[**Where and when to use Lambda in coding?**](https://www.mindstick.com/forum/159555/where-and-when-to-use-lambda-in-coding)

---

Original Source: https://www.mindstick.com/blog/304513/what-are-lambda-expressions-in-java-how-do-they-simplify-code

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