Question

Come up with a real-life problem (open-ended) and solve it by designing and writing a Java program, which implements the following java object-oriented features:

• Interaction Design

• Class and Object

• Parameterized Constructor

• Encapsulation

• Inheritance

• Abstract Method

• Method Overloading

• Method Overriding

(Add comments to code)

Answer 1

Engineer.java

public abstract class Engineer {

   //Encapsulation
   //For data privacy purpose.
   // This protected variables cannot be directly accessed by the object of the class.
   protected String university;
   protected int batch;
  
  
   //Default Constructor
   public Engineer() {
      
   }
  
   //Parameterised Constructor
   //This is also an example of overloading.
   // We can an object of this class either by default constructor or Parameterised constructor.
   public Engineer(String university, int batch) {
       super();
       this.university = university;
       this.batch = batch;
   }
  
   //Below are setters and getters for the variables of this class.
   // These methods are mandatory to get and set values for the instance variables of this class
   public String getUniversity() {
       return university;
   }
   public void setUniversity(String university) {
       this.university = university;
   }
   public int getBatch() {
       return batch;
   }
   public void setBatch(int batch) {
       this.batch = batch;
   }
  
  
   //This method will be overrided in the child class to show the overriding example
   public String getEngineerInfo() {
      
       return "University : "+this.university+"\nBatch : "+this.batch;
   }
  
  
   //Absract method.It can be defined in the child class extending this calss.
   //This is an example of abstract class.
   //Abstarct class is nothing but a methos is declared but not defined. We can do that by simply adding abstract keyword.
   public abstract String getBranch();
  
  
}

ComputerEngineer.java

public class ComputerEngineer extends Engineer{

   String branch = "Computer Science";
  
  
   public ComputerEngineer(String uni,int batch) {
       super(uni,batch);
      
   }

  

   //This is the overrided method of abstract method in the parent class Engineer.
  
   public ComputerEngineer() {
       // TODO Auto-generated constructor stub
   }

   @Override
   public String getBranch() {
       // TODO Auto-generated method stub
       return this.branch;
   }
  
  
   //This method will be overrided in the child class to show the overriding example
       public String getEngineerInfo() {
          
           return "University : "+this.university+"\nBatch : "+this.batch+"\nBranch : "+this.branch;
       }

}

EngineerTest.java

import java.util.Scanner;

public class EngineerTest {

   public static void main(String[] args) {
       // TODO Auto-generated method stub

      
       Scanner scan = new Scanner(System.in);
      
       System.out.println("Calling default Constructor");
       Engineer engineer = new ComputerEngineer();
      
       System.out.println(engineer.getEngineerInfo());
      
       System.out.println("**********************************************\n");
      
       System.out.println("Enter the university name : ");
      
       String uni = scan.next();
      
System.out.println("Enter the Batch number : ");
      
       int batch = scan.nextInt();
      
       System.out.println("Calling Parameterised Constructor");
       engineer = new ComputerEngineer(uni,batch);
      
       System.out.println(engineer.getEngineerInfo());
      
       System.out.println("**********************************************\n");
      
      
       System.out.println("Calling the abstract method implemented");
       System.out.println("Branch is : "+engineer.getBranch());
      
      
      
      
      
   }

}

Output

Calling default Constructor
University : null
Batch : 0
Branch : Computer Science
**********************************************

Enter the university name :
Stanford
Enter the Batch number :
2011
Calling Parameterised Constructor
University : Stanford
Batch : 2011
Branch : Computer Science
**********************************************

Calling the abstract method implemented
Branch is : Computer Science

Feel free to ask any doubts, if you face any difficulty in understanding.

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