Lambda Expressions in Java

Lambda expressions were introduced in Java 8 to provide a clear and concise way to represent one method interfaces using an expression. They are a key feature of functional programming in Java.

A lambda expression is essentially an anonymous function that can be used to implement functional interfaces. A functional interface is an interface that contains only one abstract method.

3.1 Basic Syntax

The basic syntax of a lambda expression is:

(parameters) -> expression

3.2 Example

interface Greeting {
    void sayHello();
}

public class Example {
    public static void main(String[] args) {
        Greeting greeting = () -> System.out.println("Hello, World!");
        greeting.sayHello();
    }
}
                

4.1 Passing Lambda Expressions

Lambda expressions are often used in functional programming concepts, particularly with the Java Collections Framework:

import java.util.Arrays;
import java.util.List;

public class LambdaExample {
    public static void main(String[] args) {
        List names = Arrays.asList("Alice", "Bob", "Charlie");
        names.forEach(name -> System.out.println(name));
    }
}
                

4.2 Using with Functional Interfaces

Common functional interfaces include:

• Runnable
• Callable
• Comparator
• Consumer
• Supplier
• Function

• Use descriptive names for lambda parameters.
• Prefer using method references when possible for cleaner code.
• Limit the use of stateful lambda expressions to avoid side effects.
• Keep lambda expressions simple and concise.