OOP prefi

Abstract Class

A class that cannot be instantiated directly and is created to ensure subclasses implement necessary methods.

Abstract Method

A method without a body that must be implemented by subclasses, declared without braces but with a semicolon.

Instantiation

The process of creating an instance of a class; an abstract class cannot be instantiated directly.

Non-Abstract Methods

Methods that can be included in an abstract class, which provide implementation.

Final Class

A class that cannot be extended or subclassed.

Concrete Class

A non-abstract class that must implement all inherited abstract methods from an abstract class.

Access Modifiers

Keywords that set the accessibility level of classes, methods, and variables; must be considered when overriding abstract methods.

Interface

A collection of related abstract public methods; can also include default methods, static methods, and constants.

Implemented Keyword

The keyword used by a class to indicate that it is implementing an interface.

Constants in Interface

Implicitly public, static, and final; keywords are not required for declaration.

Rules in Defining Abstract Classes

Includes characteristics such as not being instantiable directly and inheriting abstract methods.

Overriding Abstract Method

Declaring a new method with the same name, parameter list, and return type in the subclass.

Default Methods

Methods that can be provided in an interface with a default implementation.

Static Methods in Interface

Methods that can also be declared in an interface, although they can't be overridden.

Multi-Interface Implementation

A class can implement more than one interface at the same time.

Inheritance from Interface

An interface or an abstract class can inherit abstract methods from another interface.

Signature of Method

Unique identifiers for methods that include their name and parameter types.

Final Method

A method that cannot be overridden in a subclass.

Private Abstract Method

Not allowed; an abstract method cannot be marked as private.

Duplicate Method Signatures

A class cannot implement multiple interfaces if they contain methods with identical signatures and differing return types.

Implements Keyword

The keyword used by a class to signify it is adhering to an interface's definition.

Public Methods in Interface

All methods in an interface are implicitly public.

Defined Abstract Class

An abstract class that includes at least one abstract method.

Abstract Method Declaration

Must contain the method name, parameters, and return type but no body.

Inheritance in Abstract Classes

An abstract class that extends another abstract class will inherit all its abstract methods.

Concrete Implementation

The process whereby a concrete class fulfills all abstract method requirements.

Direct Instantiation

Not permitted for an abstract class or an interface.

Interface and Abstract Class Relationship

A class can extend an abstract class and implement an interface.

Overloading Methods in Interfaces

A class can implement interface methods that are overloaded successfully.

Class Cannot Extend Interface

Specified rule indicating an interface does not extend classes.

Abstract Method Properties

Must be accessible and cannot be final or private.

Interface Instantiation

Interfaces cannot be instantiated directly by any instance.

Keyword for Interface Definition

The interface keyword is used to declare an interface.

Method Accessibility in Subclasses

Overriding methods must be at least as accessible as parent class methods.

First Concrete Class Requirement

Must implement all inherited abstract methods from interfaces or abstract classes.

Relationship Between Interfaces

An interface can extend another interface but cannot extend a class.

Keywords Not Required for Interface

No need for public, static, and final in interface constant declarations.

Implementation of Interfaces Containing Same Method

Allowed, a class can implement multiple interfaces with the same method.

Abstract but Incomplete Interface

An interface can exist without any methods, though it is not required.

Interface Method Characteristics

All methods in interfaces are by default public and abstract unless specified otherwise.

Accessing Interface Methods

Methods are assumed to be public and can be overridden in implementing classes.

Extending Interfaces

An interface that extends another inherits all abstract methods.

Interface Definitions

Interfaces are explicitly defined using the interface keyword.