Top Java Lambda Interview Questions (2024)

1. What is Java Lambda Expressions?

2. What is Functional Interface?

3. Why use to Lambda Expression?

4. What is Java Lambda Expression Syntax?

Q: What is Java Lambda Expressions?
Ans:

The lambda expression is a new and fundamental Java feature introduced in Java SE 8. It represents one method interface using an expression in a straightforward and concise manner.

The Lambda expression is used to offer an interface implementation that has a functional interface. It saves a significant amount of code. We don't need to specify the method again in the case of a lambda expression to provide the implementation. We simply write the implementation code there.

Q: What is Functional Interface?
Ans:

The Lambda expression specifies a functional interface. A functional interface is one that has only one abstract method. The annotation @FunctionalInterface in Java is used to declare an interface as a functional interface.

Q: Why use to Lambda Expression?
Ans:

1. One advantage of using lambda expressions is that there is less code to write.
2. Support for sequential and parallel execution by passing behaviour in methods
3. When doing bulk operations on collections, we can get more performance (parallel execution) by utilising Stream APIs and lambda expressions.

Q: What is Java Lambda Expression Syntax?
Ans:

(argument-list) -> {body}  

A Java lambda expression is made up of three parts.

1. Argument-list - It can be either empty or not.
2. Arrow-token - It is used to connect the arguments-list with the body of the expression.
3. Body - It includes lambda expression expressions and statements.