Implementation of OOPS in Java

• Implementation of Abstraction
• Implementation of Encapsulation

Implementation of Abstraction :

/* File name : Employee.java */
public abstract class Employee
{
   private String name;
   private String address;
   private int number;
   public Employee(String name, String address, int number)
   {
      System.out.println("Constructing an Employee");
      this.name = name;
      this.address = address;
      this.number = number;
   }
   public double computePay()
   {
     System.out.println("Inside Employee computePay");
     return 0.0;
   }
   public void mailCheck()
   {
      System.out.println("Mailing a check to " + this.name
       + " " + this.address);
   }
   public String toString()
   {
      return name + " " + address + " " + number;
   }
   public String getName()
   {
      return name;
   }
   public String getAddress()
   {
      return address;
   }
   public void setAddress(String newAddress)
   {
      address = newAddress;
   }
   public int getNumber()
   {
     return number;
   }
}

 

/* File name : Salary.java */
public class Salary extends Employee
{
   private double salary; //Annual salary
   public Salary(String name, String address, int number, double
      salary)
   {
       super(name, address, number);
       setSalary(salary);
   }
   public void mailCheck()
   {
       System.out.println("Within mailCheck of Salary class ");
       System.out.println("Mailing check to " + getName()
       + " with salary " + salary);
   }
   public double getSalary()
   {
       return salary;
   }
   public void setSalary(double newSalary)
   {
       if(newSalary >= 0.0)
       {
          salary = newSalary;
       }
   }
   public double computePay()
   {
      System.out.println("Computing salary pay for " + getName());
      return salary/52;
   }
}

 

/* File name : AbstractDemo.java */
public class AbstractDemo
{
   public static void main(String [] args)
   {
      Salary s = new Salary("Mohd Mohtashim", "Ambehta, UP", 3, 3600.00);
      Employee e = new Salary("John Adams", "Boston, MA", 2, 2400.00);

      System.out.println("Call mailCheck using Salary reference --");
      s.mailCheck();

      System.out.println("\n Call mailCheck using Employee reference--");
      e.mailCheck();
    }
}  

Implementation of Encapsulation :

                public class EncapTest{

                      private String name;
                      private String idNum;
                      private int age;

                      public int getAge(){
                         return age;
                      }

                      public String getName(){
                         return name;
                      }

                      public String getIdNum(){
                         return idNum;
                      }

                      public void setAge( int newAge){
                         age = newAge;
                      }

                      public void setName(String newName){
                         name = newName;
                      }

                      public void setIdNum( String newId){
                         idNum = newId;
                      }
                }

Save the above code in a different file like "EncapTest.java"

            public class RunEncap{

                 public static void main(String args[]){
                       EncapTest encap = new EncapTest();
                       encap.setName("James");
                       encap.setAge(20);
                       encap.setIdNum("12343ms");

                       System.out.print("Name : " + encap.getName()+ 
                                        " Age : "+ encap.getAge());
                 }
            }

Save the above code in a different file like "RunEncap.java" If we Execute this Program it will gives the output as follows : " James 20"