Java what is the difference between an object and a class

It is a logical entity that provides the structure to create objects. In other words, the programmer can create multiple objects using one class. A class consists of attributes and methods. The attributes are the fields or methods.

Methods describe the behaviors. Furthermore, a class can also contain a constructor. It is a special method that is used to initialize an object. These attributes and methods of a class are called the members of the class. These members can have public, private or protected visibility. The public members are accessible outside the class while the private members are accessible only within the class. Moreover, the protected members are visible within the class and subclasses.

The programmer can secure the attributes of a class by declaring them as private and allow accessing them using public methods.

An object is an instance of a class. In other words, objects are created using a class. An object is an entity that has state and behaviors. The attributes of the class describe the state of an object. Similarly, the methods of a class describe the behaviors of an object. For example, the TextItem class is a template for creating an object that contains a text string.

This object will have a particular set of text attributes such as font, size, and color. If we set the values of the object variables--resources--in a certain way, we can create the TextItem object "Hello World". Resources that are available for objects of the TextItem class include the text string "Hello World" in this case , the type of font, the color of the characters, the size of the characters, the line width of the characters, etc.

A TextItem object is thus an instance of the TextItem class with a set of values assigned to the associated resources. The difference is simple and conceptual. A class is a template for objects. A class defines object properties including a valid range of values, and a default value. A class also describes object behavior. An object is a member or an "instance" of a class. An object has a state in which all of its properties have values that you either explicitly define or that are defined by default settings.

This subtle conceptual difference between classes and objects shows why there is a tendency to want to use them interchangeably. Derived classes and inheritance Sometimes it is convenient to develop a class that shares properties with another class but yet is distinct from the original.

The new class derives properties from an existing class but also extends or adds its own properties. This new class is called a "derived class" and is said to "inherit" its properties and functionality from the original class.

For example, lets say the original class is a class called Box that is defined to have two properties: side length, and color. The valid values for these properties in the Box class are: 0. If we create an instance of the Box class or, in other words, an object that is in the Box class, it will have the Box class properties side length, and color. The values of these properties will be defined as the default unless they are explicitly set. Now let's assume we want to create a box object that is filled rather than the hollow boxes created using the Box class template.

Instead of creating a completely new template that has many of the same properties of the Box class, we can derive a new class and extend the functionality of the derived class as necessary to create a class that defines filled box objects. FilledBox will be the name of the derived class.

Java Objects are designed as class hierarchies. A Class in object oriented programming is a blueprint or prototype that defines the variables and the methods functions common to all Java Objects of a certain kind. An object in OOPS is a specimen of a class. Software objects are often used to model real-world objects you find in everyday life.

You will need various information about the dogs like different breeds of the dogs, the age, size, etc. Some of the differences you might have listed out maybe breed, age, size, color, etc. If you think for a minute, these differences are also some common characteristics shared by these dogs.

These characteristics breed, age, size, color can form a data members for your object. Next, list out the common behaviors of these dogs like sleep, sit, eat, etc. So these will be the actions of our software objects. Now, for different values of data members breed size, age, and color in Java class, you will get different dog objects. In previous program, we are creating main method inside the class. Now, we create classes and define main method in another class.