What is an object and how are they created in object oriented programming languages?

Answer 1

Objects are the examples of the idea which the class represents. Objects of a class are constructed using the "new" keyword. For example: class Person { String name; } class Earth { public static void main(String... args) { Person sunny = new Person(); // Creating Object sunny.name = "Sunny"; } } Here, we have a class Person, the object of this class (in this case a person having name Sunny) is created from another class Earth using the keyword "new".

Answer 2

an object of the type you want is instantiated (created) by calling its constructor such as shown below:

the "new" keyword is needed as it tells the compiler to create a new object of type MyClass.

<code>

//creates an instance of a MyClass() Object

MyClass() <nameOfVariable> = new MyClass(<parameters>);

</code>

Answer 3

Classes are the definitions of user-defined data structures.

Objects are concrete instances of classes.

Here's an analogy:

Think of what the word chair means to you. It has four legs, a back, and a seat. So you can call this your concept on what it means to be a chair. The one you are sitting on as you read this is a specific instance of a chair.

so... the concept of "chair" is analogous to a class... whereas the chair you are sitting on is analogous to an object of the "chair" class.

Sorry if that was confusing.

Answer 4

In object-oriented programming, objects are instances of a class. The class definition is essentially the definition of an user-defined type. You instantiate an instance of that type be declaring a variable of that type. The variable is therefore an object -- an instance of the class. If the variable is a pointer to the type, then the pointer may either refer to an existing instance, or it may refer to a new instance by calling the new operator. In the latter case (dynamic instantiation), you must maintain at least one pointer to this instance in order to release the memory back to the system.

Answer 5

To bluntly answer your question, yes there is a difference between an object and a class.

A class is literally what you see when you write a class. It is the code, not yet compiled, which defines said Class.

An object is merely an instance of a class.

To create a new instance of, for example, the Scanner object (in java.util.*), you do the following:

Scanner varNameCanBeAnything = new Scanner(System.in);

the syntax is

Object varNameCanBeAnything = new Object(parameters);

If you read this backwards, it becomes easier to understand. The Scanner object is defined in the util class. So instead of reading it like java.util.Scanner, try looking at it as Scanner.util.java -- if it makes it easier for you. Just remember that an Object is only an instance of a class.

Hope this helps!

Answer 6

An object is an instance of a class. You create an object through instantiation.

// Define the class...

class Foo {/*...*/};

// Instantiate the class...

Foo x;

When you instantiate a class, a class constructor is invoked. If you do not declare any constructors in your class, the compiler generates a default constructor, a copy constructor and a move constructor, all of which have public access. Thus the above definition if Foo is equivalent to the following definition:

// Define the class... class Foo {

public:

Foo (); // default constructor

Foo (const Foo&); // copy constructor

Foo (Foo&&); // move constructor

};

In most cases, the compiler-generated constructors will suffice, so we only need to define constructors when we wish to override the default implementation of the compiler-generated constructors. However, if we define any constructor that accepts one or more arguments, the compiler-generated default constructor is no longer generated; we must explicitly define one if we require one. The compiler-generated copy and move constructors are always generated unless we explicitly delete them or override them with our own implementations.

Note that constructors are used specifically to initialise the class invariants.

Answer 7

Lets say you have a class Employee.

public class Employee {

......

}

In another class Management you want to instantiate an object of type Employee.

public class Management {

..........

Employee obj = new Employee();

}

This is how you create an object of a class.

Answer 8

three types of creating objects.

1)using new keyword

2)class.forName

3)factory method