Java Classes and Objects Vocabulary

Questions and Answers

What is an object in programming?

A software blueprint

A programming language

A method in a class

Every program that involves something being created or manipulated (correct)

What is a class?

A software blueprint for implementing objects of a given type.

What are public methods?

Methods accessible to all client programs.

What does encapsulation mean?

Combining an object's data and methods into a single unit called a class. Signup and view all the answers

What is information hiding?

Restriction of access. Signup and view all the answers

What are private methods and variables?

Methods and variables that can only be accessed by the methods of their class. Signup and view all the answers

What is a static variable?

A variable that contains a value shared by all instances of the class. Signup and view all the answers

What does a driver class contain?

The main method. Signup and view all the answers

What is the purpose of an access specifier?

It tells which other methods can call this method (public, private, static). Signup and view all the answers

What is a return type?

It indicates what type is returned, void means nothing. Signup and view all the answers

What do constructors do?

They create an object of the class. Signup and view all the answers

What is a default constructor?

A constructor that has no argument and provides reasonable initial values for an object. Signup and view all the answers

What are object variables?

They provide a memory location to an object and do not store the objects themselves. Signup and view all the answers

What are accessors?

Methods that access a class object and return information without altering the object. Signup and view all the answers

What are mutators?

Methods that change the state of an object by modifying at least one instance variable. Signup and view all the answers

What are instance methods?

Methods that operate on individual objects of a class. Signup and view all the answers

What are static methods?

Methods that perform an operation for the entire class, not its individual objects. Signup and view all the answers

What are overloaded methods?

Two or more methods in the same class that have the same name but different parameters. Signup and view all the answers

What does the signature of a method consist of?

The method's name and a list of the parameter types. Signup and view all the answers

What is scope in programming?

The region in which a variable or method is visible and can be accessed. Signup and view all the answers

What is a block of code?

A piece of code enclosed in a {} pair. Signup and view all the answers

What is a local variable?

A variable defined inside a method or block. Signup and view all the answers

What does 'this' refer to in programming?

The object is an implicit parameter for the method, referred to with the 'this' keyword. Signup and view all the answers

What is aliasing?

Having two references for the same object, causing unintended problems. Signup and view all the answers

What are null references?

References that point to an uninitialized object. Signup and view all the answers

What are formal parameters?

The new variable names in a parameter list that serve as placeholders. Signup and view all the answers

Study Notes

Object-Oriented Programming Concepts

Object: Fundamental unit in programming that represents something being created or manipulated.
Classes: Blueprints for creating objects of a specific type, defining their properties and behaviors.

Method Types and Access

Public Methods: Accessible from any client program, allowing interaction with the object's functions.
Private Methods and Variables: Restricted access, only callable within the defining class to maintain encapsulation.
Static Variable (Class Variable): Shared across all instances of a class, maintaining a single value for the entire class.

Encapsulation & Information Hiding

Encapsulation: Combines data and methods within a single structure, promoting modularity.
Information Hiding: Limits access to certain data, enhancing security and reducing complexity.

Constructors

Constructors: Specialized methods used to create and initialize a new object of a class.
Default Constructor: Constructor without parameters that assigns default values to an object's attributes.

Method Characteristics

Return Type: Specifies the type of data returned by a method; 'void' indicates no return value.
Access Specifier: Determines the visibility of methods (e.g., public, private).
Signature of a Method: Unique identification based on the method name and the types of its parameters.

Variable Scope

Local Variable: Declared within methods or blocks; only accessible within that context.
Scope: Defines the visibility range of variables and methods within the code.

Method Functionality

Instance Methods: Work on specific instances of a class, allowing for object-specific behaviors.
Static Methods: Operate on a class level, affecting all instances rather than individual objects.
Overloaded Methods: Multiple methods share the same name but differ in their parameter types, enhancing flexibility.

Accessing and Modifying Objects

Accessors: Methods that retrieve information from an object without changing its state.
Mutators: Methods that modify an object's state, typically affecting one or more instance variables.

Memory Management

Block: Code segment enclosed in braces {}; local variables' memory is released when the block is exited.
Null Reference (Null Pointer): Indicates that an object has not been initialized, leading to potential errors if accessed.
Aliasing: Occurs when multiple references point to the same object, which can create unexpected issues.

Additional Concepts

Driver Class: Contains the main method where program execution begins.
Object Variables: Variables that hold references to objects; they point to memory locations rather than storing objects directly.
Formal Parameters: Variable placeholders in method definitions, representing the arguments passed during method calls.

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