Top 10 Java Lambda Interview Questions and Answers

Master Java Lambda expressions with these top 10 interview questions and answers. Learn syntax, functional interfaces, real-world examples, and key differences.

Java Lambda Expressions introduced in Java 8 brought functional programming into the Java world. They allow you to write cleaner, more expressive, and concise code by replacing verbose anonymous classes.

In this article, we’ll explore the top 10 Java Lambda interview questions for 2025.

1️⃣ What is a Lambda Expression in Java?

A lambda expression is a short block of code that takes in parameters and returns a value. It allows you to implement functional interfaces (interfaces with only one abstract method) without writing a separate class.

Lambda expressions are useful because they reduce boilerplate code and make your logic more readable.

Without a Lambda expression, you can see the code:

class ThreadDemo implements Runnable {
    @Override
    public void run() {
        System.out.println("Thread is running...");
    }
}

public class LambdaThreadExample {
    public static void main(String[] args) {
        Thread thread = new Thread(new ThreadDemo());
        thread.start();
    }
}