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Objects in Java
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Objects in Java contains the information that describes the attributes (states) and the characteristics (methods) of a class. You can have several objects from the same class, where each object is unique! Said that an object is an instance of a class.
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WHAT IS A OBJECT IN JAVA?
An object is an instance of a class and contains the information that the class specifies that the object must have; that is, the attributes (states) and the properties (methods). Often you create several objects from the same class. The objects are then entirely independent of each other, even though they come from the same class, often called encapsulation. Encapsulation means that the object is completely independent of other objects or code since the object only performs what we instruct it to do. Therefore, a programmer only needs to know how to communicate with the object, without knowing how the object performs the task
An object in Java is:
- An instance of a class.
- Encapsulated, which means it is independent of any other code.
- Has the attributes that are specified at instantiation.
- It can perform the methods specified in the corresponding class.
- Even two objects from the same class are independent of each other.
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HOW TO USE OBJECTS IN JAVA?
An object in Java can be just about anything. An object contains information about the object’s condition (for example, color and year model of a car). Objects also contain information on how the object behaves, which is specified in the class’s methods (for example, driving forward or turning for a car). An object in Java can be just about anything, as it is up to you to decide how the object is defined when you create the class. Therefore, create several small models (classes) of the entire program where each building block is its own class!
It is usually said that an object is an instance of a class.
It is usually said that an object is an instance of a class. The properties to be defined when creating an object are therefore naturally called instance variables. Each object can have different instance variables, even though they come from the same class. Two objects from the same class are, therefore, completely independent of each other! This way of building programs is called object-oriented programming; every part of the program does its role in the program![/vc_column_text][vc_empty_space height=”20px”][vc_column_text]
Example – Using OBJECTs IN JAVA
In the previous page we described the dog class according to:
class Dog {
// Defines the Attributes of the dog class
String name;
int age;
String breed;
String color;
// Defines the methods for the dog class
void bark(){
}
void eat(){
}
void sleep(){
}
}
[/vc_column_text][vc_empty_space height=”15px”][vc_single_image image=”20109″ img_size=”large” alignment=”center” onclick=”link_image” qode_css_animation=””][vc_empty_space height=”15px”][vc_column_text]Say that we want to create more than one dog when programming. Thanks to classes and objects we can use the same class to create several objects of the same kind (it would be very tedious and time-consuming if we needed to create a separate class for each dog).
In this example we want two dogs, in other words, two items from the same class:[/vc_column_text][vc_empty_space height=”50px”][vc_row_inner row_type=”row” type=”full_width” text_align=”left” css_animation=””][vc_column_inner width=”1/3″][vc_column_text]Dog 1:
Name: Brady
Age: 3
Breed of dog: Terrier
Color: Brown[/vc_column_text][vc_empty_space height=”40px”][/vc_column_inner][vc_column_inner width=”2/3″][vc_single_image image=”20112″ img_size=”large” alignment=”center” onclick=”link_image” qode_css_animation=””][/vc_column_inner][/vc_row_inner][vc_empty_space height=”40px”][vc_row_inner row_type=”row” type=”full_width” text_align=”left” css_animation=””][vc_column_inner width=”1/3″][vc_column_text]Dog 2:
Namn: Steven
Age: 5
Breed of dog: Pudel
Color: Black[/vc_column_text][vc_empty_space height=”40px”][/vc_column_inner][vc_column_inner width=”2/3″][vc_single_image image=”20113″ img_size=”large” alignment=”center” onclick=”link_image” qode_css_animation=””][/vc_column_inner][/vc_row_inner][vc_empty_space height=”20px”][vc_column_text]As you can see, the two dogs are different, but we can still use the same class to create the objects (they all have the same properties – the instance variables)! This is very useful when programming multiple objects of the same kind. Perhaps you want to program an entire kennel?
To create an object you use a constructor. More about the constructor on the next page.[/vc_column_text][vc_empty_space height=”30px”][vc_column_text]
WHAT IS THE DIFFERENCE BETWEEN OBJECTS AND A CLASS?
A class is a template of what an object should look like. The class specifies which properties (methods) and which attributes (states) the object should have. From the class, you can create, instantiate an object. Then you specify what state each object should have. All objects are independent of each other, even though they come from the same class.[/vc_column_text][vc_empty_space][vc_separator type=”normal” thickness=”2″][vc_empty_space][/vc_column][/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern”][vc_column][vc_column_text]
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