Java: OOP (Part 1)

Java

____ is an object-oriented programming language

Object-oriented

______ programming organizes a program around its data and a set of well-defined interfaces to that data

class, instantiated

In Java, the unit of programming is the ___ from which objects are _____

methods, fields

Java classes contain ____ (which implement operations) and ____ (which implement attributes)

class

A ____ is a blueprint from which individual objects are created

class

A class is declared by use of the _____ keyword

Local variables

______ are defined inside methods, constructors or blocks

Instance variables

_____ are variables within a class but outside any method

Class variables, static

______ are variables declared within a class, outside any method, with the ___ keyword

Constructor

_____ in Java is a special type of method that is used to initialize the object

constructor

Every class has a ______

more than one

A class can have _____ constructor

class

The main rule of constructors is that they should have the same name as the ____.

new

In Java, the ___ keyword is used to create new objects

memory, address

The new operator dynamically allocates ____ for an object and returns a reference to it. This reference is the _____ in memory of the object allocated by new keyword

Declaration
Instantiation
Initialization

Three steps to create an object

Declaration

variable declaration (name with an object type)

Instantiation

using the new keyword to create the object

Initialization

new keyword is followed by a call to a constructor

objects

Instance variables are accessed via created _____

First create an object
Call the instance variable

To access an instance variable:

objects

Instance methods are accessed via created _____

First create an object
Call the instance method

To access an instance method:

Java method

A ______ is a collection of statements that are grouped together to perform a specific operation

type modifier

defines the access type of the method and it is optional to use

return type

method may return a value

method name

name of the method

argument list

list of parameters, it is the type, order, and number of parameters of a method. These are optional, method may contain zero parameters

method body

defines what the method does with statements

static

A method that has static keyword is known as ___ method

instance

The method of the class is known as an _____ method

instance method

It is a non-static method defined in the class

object

Before calling or invoking the instance method, it is necessary to create an _______ of its class

accessor, getters

The method that reads the instance variable is known as the _____ method. is also known as _____

get

The accessor method is prefixed with the word ____

private

Accessor method returns and used to get the value of the _____ field

mutator, setters, modifiers

The method that read the instance variable and also modify the values is known as the _____ method. It is also known as _____ or ______

void

The ____ keyword allows us to create methods which do not return a value

public
default
protected
private

Access modifier by hierarchy:

Local variable
Instance variable
Class variable

Types of variables

Static method
Instance method
Accessor method
Mutator method

Types of methods