Java Class Diagram Concepts

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.