Learn Object-Oriented Programming in Java/

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Declaration and Implementation

Declaration and Implementation

In this lesson, you will learn about the declaration and implementation details of a class.

We'll cover the following...

The written code of a class and its attributes are known as the definition or implementation of the class.

Declaration

In Java, we define classes in the following way:

Java
class ClassName { // Class name
  
  /* All member variables
  and methods*/
}

The class keyword tells the compiler that we are creating our custom class. All the members of the class will be defined within the class scope.

Creating a class object

The name of the class, ClassName, will be used to create an instance of the class in our main program. We can create an object of a class by using the keyword new:

Java
class ClassName { // Class name
  ...
    // Main method
    public static void main(String args[]) {
    ClassName obj = new ClassName(); // className object
    
  }
}

Implementation of a Car class

Let’s implement the Car class illustrated below:

Java
//The Structure of a Java Class
class Car { // Class name
  
  // Class Data members
  int topSpeed;
  int totalSeats;
  int fuelCapacity;
  String manufacturer;
  
  // Class Methods
  void refuel(){
    ...
  }
  void park(){
    ...
  }
  void drive(){
    ...
  }
  
}