Java Class Diagram Concepts

Questions and Answers

What determines which other classes have access to a class?

Access Modifier

What keyword allows us to add to existing classes?

extends OldClassName

What keyword indicates a class will provide code for each item specified in an interface?

implements InterfaceName

What are primitive data and objects that contain the state of an object called?

Fields Signup and view all the answers

What provides the code needed to create and initialize an object as defined by its class?

constructor Signup and view all the answers

What method type does the internal work for a class that users don’t need to worry about?

private methods Signup and view all the answers

What are the programming interfaces of a class to other classes called?

public methods Signup and view all the answers

What elements can be a class, block, method, or variable that members do not need an object to access?

Static elements Signup and view all the answers

What is the major executable part of a class or program that is static and has a void return type?

static main method Signup and view all the answers

What is used to initialize static fields of a class, executing once when the class is loaded?

static block Signup and view all the answers

Study Notes

Access Modifiers

Defines the accessibility level of classes; includes public, private, and default.
Public classes are accessible by any other class, while private classes can only be accessed within their enclosing class.

Inheritance (extends)

The extends keyword enables a class to inherit methods and fields from an existing class.
Supports polymorphism, allowing one interface to be used for different underlying forms.

Interfaces (implements)

The implements keyword specifies that a class will provide implementations for all methods in an interface.
Facilitates polymorphism through composition, enabling the class to have multiple behaviors.

Fields

Represent the state of an object, consisting of primitive data types and objects.
Typically marked as private to encapsulate data, except for constants which may be public.

Constructors

Special methods for creating and initializing new object instances of a class.
Must be invoked following the new keyword during object creation.

Private Methods

Perform internal operations of a class that are not intended for user interaction or access.
Help maintain encapsulation and prevent external interference.

Public Methods

Serve as the interface for other classes to interact with the class.
Ensure controlled access to private fields and methods, encapsulating the internal workings.

Static Elements

Can include static classes, methods, variables, or blocks that belong to the class itself rather than instances.
Shared across all instances of the class, inherently accessible without object instantiation.

Static Main Method

A mandatory static method with a void return type that functions as the entry point of a Java application.
Responsible for initiating class testing or program execution.

Static Block

Used to initialize static fields of a class, executed once when the class is loaded into memory.
Can also initialize static fields that have been imported, aiding in the setup of class-level variables.

Description

Test your knowledge of key concepts in Java class diagrams. This quiz covers fundamental terms such as access modifiers, inheritance, and interfaces. Perfect for anyone looking to strengthen their understanding of object-oriented programming in Java.