Question

Define a class Bill that calculates the telephone bill of a consumer with the following description: 

Instance variables/Data members:
int bno: bill number
String name: name of consumer
int call: no. of calls consumed in a month
double amt: bill amount to be paid by the person
Member methods
Bill(): constructor to initialize data members with default initial value
Bill(...): parameterised constructor to accept bill no, name and no. of calls consumed.
Calculate(): to calculate the monthly telephone bill for a consumer as per the following condition

Units consumed	Rate
First 100 calls	₹ 0.60/call
Next 100 calls	₹ 0.80/call
Next 100 calls	₹ 1.20/call
Above 300 calls	₹ 1.50/call

Fixed monthly rental applicable to all consumers: ₹ 125
Display(): to display the details

Create an object in the main() method and invoke the above functions to perform the desired task.

Answer 1

import java.util.*;
class Bill{
int bno; // bill number
String name;
int call; // no. of calls made
double amt;

Bill()
{ // System.out.println("Default constructor called");
bno = 0;
name = "";
call = 0;
amt = 0.0D;
}

Bill (int num, String nm, int c)
{ // System.out.println("Parameterized constructor called");
bno = num;
name = nm;
call = c;
}

void calculate()
{if (call <= 100)
   amt = 0.60 * call;
else if (call > 100 && call <= 200)
   amt = (0.60 * 100) + (call - 100) * 0.80;
else if (call > 200 && call <= 300)
   amt = (0.60 * 100) + (0.80 * 100) + (call - 200) * 1.20;
else if (call > 300)
   amt = (0.60 * 100) + (0.80 * 100) + (100 * 1.20) + (call - 300) * 1.50;

amt += 125; // RS.125 RENT IS APPLICABLE TO ALL CUSTOMERS
}

void display()
{
System.out.println("Bill No.: " + bno);
System.out.println("Name: " + name);
System.out.println("No. of calls: " + call);
System.out.println("+ Rent Rs. 125");
System.out.println("Total Amount: " + amt);
}

public static void main(String args[])
{Scanner ob = new Scanner(System.in);
int a, c;
String b;
Bill b1 = new Bill(); // Invoke default constructor
System.out.println("Enter the Bill number");
a = ob.nextInt(); N
System.out.println("Enter the Customer name");
b = ob.nextLine();
ob.nextLine(); // to eliminate nextLine()issues
System.out.println("Enter the No.Of.Calls made");
c = ob.nextInt();
Bill b2 = new Bill(a, b, c); // Invoke parameterized constructor
b2.calculate();
b2.display();
}}