Anonymous Classes in Java Flashcards

Questions and Answers

What is the big idea of anonymous classes?

Requires multiple Java files

Defines a class with multiple methods

Implements an interface with a single method easily (correct)

Creates instances of interface with complex structure

What are anonymous classes and lambda expressions used for?

Ways to quickly make an instance of an interface without needing to create a new Java file.

How do you implement an interface with an anonymous class?

Use the new keyword since a new instance is created and define the class methods in the anonymous class body.

The syntax for a Lambda expression is: Fan tarheel = (Game g) --> { ... };

<p>Fan tarheel = (Game g) --> { if (g.whoIsWinning().equals('UNC')) { System.out.println('Go heels'); } };</p> Signup and view all the answers

What does the anonymous class for Fan look like?

<p>Fan tarheel = new Fan() { @Override public void update(Game g) { if (g.whoIsWinning().equals('UNC')) { System.out.println('Go heels'); } } };</p> Signup and view all the answers

Study Notes

Big Idea

Interfaces with a single method allow for straightforward class definition and instance creation.
Emphasizes the convenience of implementing an interface without excessive boilerplate code.

Anonymous Classes and Lambda Expressions

Provide a mechanism to create an instance of an interface quickly.
No need for a separate .java file, suitable for single-use instances.

Implementing an Interface with an Anonymous Class

A new instance is created using the new keyword.
Class methods are defined directly within the anonymous class body, allowing for customized behavior.

Lambda Expression

Allows concise representation of a functional interface.
Example: Fan tarheel = (Game g) --> { if (g.whoIsWinning().equals("UNC")) { System.out.println("Go heels"); } };
Highlights the simplicity of defining a behavior in a single line.

Anonymous Class

Provides a way to define a subclass at the point of instantiation.
Example: Fan tarheel = new Fan() { @Override public void update(Game g) { if (g.whoIsWinning().equals("UNC")) { System.out.println("Go heels"); } } };
Enables immediate customization of existing classes without needing additional files.

Description

This set of flashcards covers the concept of anonymous classes and their comparison to lambda expressions in Java. You'll learn how to implement single-method interfaces without creating separate classes, streamlining your coding process. Perfect for Java programmers looking to enhance their understanding of concise class definitions.