Java class is nothing but a template for object you are going to create or it’s a blue print by using this we create an object. In simple word we can say it’s a specification or a pattern which we define and every object we define will follow that pattern.
What does Java Class Consist
When we create class in java the first step is keyword class and then name of the class or identifier we can say.
Next is class body which starts with curly braces {} and between this all things related with that class means their property and method will come here.
Template is:
Class (name of the class) {
(Here define member of class)
}
Access level of class:
Java class has mainly two type of access level:
Default: class objects are accessible only inside the package.
Public: class objects are accessible in code in any package.
What are members of Class?
When we create a class its totally incomplete without defining any member of this class same like we can understand one family is incomplete if they have no members.
Field: field is nothing but the property of the class or object which we are going to create .for example if we are creating a class called computer then they have property like model, mem_size, hd_size, os_type etc
Method: method is nothing but the operation that an object can perform it define the behavior of object how an object can interact with outside world .startMethod (), shutdownMethod ().
Access Level of members: Access level is nothing but where we can use that members of the class.
Each field and method has an access level:
- private: accessible only in this class
- package or default: accessible only in this package
- protected: accessible only in this package and in all subclasses of this class
- public: accessible everywhere this class is available
Real world example of Class in Java Programming:
In real world if we want to understand about the class everything of same quality can be visualize as a class e.g. men,women,birds ,bicycles ,cars or we can say vehicle .
The entire vehicle will make one class they have the property like no_of_wheels, color, model, brand etc.now we can think changeGear () and speedOfvehicle (), applyBreak () etc as a method on that class. Similarly all human being also can be one class now their member will be a men ,women ,child.,isAlive() ,isDeath() can be their method or behavior of that class .again we can make Men or women a separate class and define their property and method accordingly,
In short in java every problem we get solution can be think in terms of class and object.
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Java