Java Anonymous Classes and Lambdas Flashcards

Questions and Answers

What alternatives are there to inner classes?

Anonymous classes

What is an example of an anonymous class?

A new class of Iterator with an implementation.

What are the key elements of anonymous classes?

They are inner classes with no name and can be defined at the point of instantiation.

What are lambdas in Java?

Simpler syntax for an anonymous class that subclasses an interface with one method. Signup and view all the answers

Criteria for having lambdas include that you must implement an ______.

interface Signup and view all the answers

What is the syntax of lambda expressions?

They use the -> operator. Signup and view all the answers

What happens under the hood when we create a lambda?

A class is created that implements the interface, an instance of that class is created, and a reference to the object is provided. Signup and view all the answers

What is variable capture in lambdas?

Lambda expressions can capture final variables and non-final variables from their surroundings. Signup and view all the answers

Study Notes

Anonymous Classes

Inner classes can be cumbersome when only used once; anonymous classes offer a solution by being unnamed inner classes.
They simplify code structure by avoiding the need to define a separate class for single-use instances.

Iterator Interface Example

Anonymous classes can be created on-the-fly to implement interfaces like Iterator.
This demonstrates the convenience and flexibility of using anonymous classes.

Key Elements of Anonymous Classes

Often used to instantiate an interface or extend a superclass without creating a separate named class.
They provide a way to enhance existing code without cluttering the namespace.

Understanding Lambdas

Lambdas are a concise syntax that simplify the creation of anonymous classes specifically for interfaces with one method.
They improve readability and reduce boilerplate code in Java.

Criteria for Using Lambdas

An interface must be implemented, specifically a functional interface with a single abstract method.
Lambdas streamline method implementation, making it more efficient.

Lambda Expressions Syntax

Lambda expressions utilize the -> operator, indicating the transition from parameters to the expression body.
The left side of -> contains parameters (optional brackets), while the right side contains the expression that yields the result.
Single-expression lambdas do not require explicit return statements or curly braces.

Underlying Mechanism of Lambdas

When a lambda is created, Java automatically generates a class that implements the specified interface.
An instance of this class is created, and a reference to the object is provided, enabling its use.

Variable Capture in Lambdas

Lambdas can capture final variables from their context, allowing them to access these external values.
Non-final variables can also be captured, effectively creating a copy for use within the lambda.
Lambdas can reference member variables directly through this.

Description

Explore the concepts of anonymous classes and lambdas in Java through interactive flashcards. This quiz will help you understand alternatives to inner classes and practical examples, including the usage of interfaces like Iterator.