Exercise User Defined Class 2

Task 1

Type the above definition of a Triangle class and save in a file.

1.     What is the name to be given to this file?

Triangle

2.     Compile this file.  If you get any error, it means that you haven’t typed correctly the given codes.

No error detected.

3.     After a successful compilation, now try to run. Explain what happened and why.

Cannot run because there is no main method.

Task 2

Complete the above Java program and save it in the same folder where the Triangle class file is located.

 

1.     Compile this file.  If you get any error, it means that you haven’t typed correctly the given codes.

import java.util.Scanner;

public class TriangleDemo {

    public static void main(String[] args)

   {

      //create a Scanner object

      Scanner input = new Scanner(System.in);

      // Create a Triangle object.

      Triangle triangle = new Triangle();//using java default if takde constructor

      // Prompt user to input value for height and base                 

      System.out.println("Enter Height: ");

      double height = input.nextDouble();

      System.out.println("Enter base: ");

      double base = input.nextDouble();

             // Create a Triangle object.

 // Triangle triangle = new triangle (height,base);

      //Set the height and base

      triangle.setHeight(height);

      triangle.setBase(base);

    //triangle.set(height,base):

      // Display the height, base and area 

      System.out.println("The pyramid's height is "

                         + triangle.getHeight());

      System.out.println("The pyramid's base is "

                         + triangle.getBase());

      

     System.out.println("The pyramid's area is "

                         + triangle.getArea());

      

   }

}

2.     After a successful compilation, now try to run. What’s the output?

3.    List ALL the following items based on the Triangle class:

 

a) user-defined methods with return value

 all the accessor method. Eg: getHeight();

b) user-defined methods with passing-parameters 

all mutator method. Eg: triangle.setHeight();

c) accessor methods

triangle.getBase

d) mutator methods

       triangle.setBase

4. Replace the set() method with a constructor. Modify the main() method.

package triangledemo;

import java.util.Scanner;

public class TriangleDemo {

   

   public static void main(String[] args)

   {

      //create a Scanner object

      Scanner input = new Scanner(System.in);

      

      // Prompt user to input value for height and base                 

      System.out.print("Enter height:  ");   

      double height = input.nextDouble();     

      System.out.print("Enter base:  ");     

      double base = input.nextDouble();

      // Create a Triangle object.

      Triangle triangle = new Triangle(height,base);

      //Set the height and base (use mutator) 

      triangle.setHeight(height);

      triangle.setBase(base);

      // Display the height, base and area (use accessor)

      System.out.println("The pyramid's height is "

                         + triangle.getHeight());

      System.out.println("The pyramid's base is "

                         + triangle.getBase());

      

     System.out.println("The pyramid's area is "

                         + triangle.getArea());

     test(height, triangle);

     System.out.println("height value: +height ");

   }

   public static void test(double height, Triangle traingle){

       height = 33.99;

       triangle.setHeight(13.5);

   }

}

Task 3

Develop an Employee class which consists of employee ID number, gross pay, state tax and federal tax. You also must create input () method to prompt a user to insert employee ID number, gross pay, state tax and federal tax.Next, develop a Payroll class that consists of two user-defined methods, namely calculateNetPay() and printOutput() methods.  

import java.util.Scanner;

public class Employee {

    private String empID;

    private double grossPay;

    private double stateTax;

    private double federalTax;

    

    public double getGrossPay(){

        return grossPay;

    }

    public double getStateTax(){

        return stateTax;

    }

    public double getFederalTax(){

        return federalTax;

    }

    public void input(){

    Scanner sc = new Scanner (System.in);

    System.out.print("Enter your employee ID number: ");

    empID = sc.next();

    System.out.print("Enter your Gross Pay: ");

    grossPay = sc.nextDouble();

    System.out.print ("Enter your State Tax:  ");

    stateTax = sc.nextDouble();

    System.out.print ("Enter your Federal Tax:   ");

    federalTax = sc.nextDouble();

    }

}

public class Payroll  {

    private double netPay;

    public void calculateNetPay(Employee e){

        netPay = e.getGrossPay()- e.getStateTax()- e.getFederalTax();

    }

    public void printOutput() {

       System.out.printf("Net pay is: RM %.2f", netPay);

      

  }

}

 public class PayrollDemo {

    public static void main (String[] args){

        Employee e = new Employee();

        e.input();

        Payroll p = new Payroll();

        p.calculateNetPay(e);

        p.printOutput();

    }

public class PayrollDemo {

    public static void main (String[] args){

        //Array of object Employee

        Employee [] arrEmp = new Employee[2];

       

        for (int i=0; i<arrEmp.length;i++ ){

            Employee e = new Employee();

            arrEmp[i]=e;

            e.input();

        }

        for (int i=0; i<arrEmp.length;i++ ){

            Payroll p = new Payroll();

            p.calculateNetPay(arrEmp[i]);

            System.out.println("Employee ID "+arrEmp[i].getEmpID());

            p.printOutput();

        }

      //  Employee e = new Employee();

       // e.input();

        //Payroll p = new Payroll();

        //p.calculateNetPay(e);

       // p.printOutput();

    }

}