# Homework on Constructors

## Question 1

Define a class number described as below:
Data members:
a and b of int type.
Member methods:
a) A default constructor to initialize the data members.
b) sum() to return the sum of a and b.
c) display() to display the values of a and b.
In the main() method, create an object and call the above mentioned methods.

``````class number{
int a;
int b;
public number(){
a = 12;
b = 7;
}
public int sum(){
return a + b;
}
public void display(){
System.out.println("a = " + a);
System.out.println("b = " + b);
}
public static void main(String[] args){
number obj = new number();
obj.display();
System.out.println("Sum = " + obj.sum());
}
}``````

## Question 2

Define a class SalaryCalculation described as below:
Data members:
name (String data type)
basicPay, specialAlw, conveyanceAlw, gross, pf, netSalary, annualSal (double data types)
Member methods:
a) SalaryCalculation(): A constructor to assign name of employee (name), basic salary (basicPay) of your choice and conveyance allowance (conveyanceAlw) as Rs. 1000.00.
b) void salaryCal(): To calculate other allowances and salaries as given below:
specialAlw = 25% of basic salary
pf = 11% of basic salary
gross = basicPay + specialAlw + conveyanceAlw
netSalary = gross – pf
annualSal = 12 months of net salary
c) void display(): To display the name and other calculations with suitable headings.
Write a main() method to call the above member methods.

``````class SalaryCalculation{
String name;
double basicPay;
double specialAlw;
double conveyanceAlw;
double gross;
double pf;
double netSalary;
double annualSal;
public SalaryCalculation(){
name = "James Gosling";
basicPay = 110000.0;
conveyanceAlw = 1000.0;
}
public void salaryCal(){
specialAlw = 0.25 * basicPay;
pf = 0.11 * basicPay;
gross = basicPay + specialAlw + conveyanceAlw;
netSalary = gross - pf;
annualSal = 12 * netSalary;
}
public void display(){
System.out.println("Employee name: " + name);
System.out.println("Basic Pay: " + basicPay);
System.out.println("Special Allowance: " + specialAlw);
System.out.println("Conveyance Allowance: " + conveyanceAlw);
System.out.println("Gross: " + gross);
System.out.println("PF: " + pf);
System.out.println("Net Salary: " + netSalary);
System.out.println("Annual Salary: " + annualSal);
}
public static void main(String[] args){
SalaryCalculation obj = new SalaryCalculation();
obj.salaryCal();
obj.display();
}
}``````

## Question 3

Define a class PhoneBill with the following descriptions:
Data members:
customerName of String type
phoneNo of long type
no_of_unit of int type
rent of int type
amount of double type
Methods:
PhoneBill(): to initialize with default value to each data member.
accept(): to accept customer name, phone number, number of units and rent.
calculate(): to calculate the amount as rent + cost for the units, where cost for the units is to be calculated according to the following conditions:
First 50 calls: Free
Next 100 calls: Rs. 0.80/unit
Next 200 calls: Rs. 1.00/unit
Remaining calls: Rs. 1.20/unit
display(): to display the values of all the data members on the screen.

``````import java.io.*;
class PhoneBill{
String customerName;
long phoneNo;
int no_of_unit;
int rent;
double amount;
public PhoneBill(){
customerName = "";
phoneNo = 0L;
no_of_unit = 0;
rent = 0;
amount = 0.0;
}
public void accept()throws IOException{
System.out.print("Customer's name: ");
System.out.print("Phone Number: ");
System.out.print("Number of units: ");
System.out.print("Rent: ");
}
public void calculate(){
if(no_of_unit <= 50)
amount = 0.0;
else if(no_of_unit <= 150)
amount = (no_of_unit - 50) * 0.80;
else if(no_of_unit <= 350)
amount = 100 * 0.80 + (no_of_unit - 150) * 1.00;
else
amount = 100 * 0.80 + 200 * 1.00 + (no_of_unit - 350) * 1.20;
amount += rent;
}
public void display(){
System.out.println("Customer Name: " + customerName);
System.out.println("Phone Number: " + phoneNo);
System.out.println("Number of units: " + no_of_unit);
System.out.println("Rent: Rs. " + rent);
System.out.println("Amount: Rs. " + amount);
}
public static void main(String[] args)throws IOException{
PhoneBill obj = new PhoneBill();
obj.accept();
obj.calculate();
obj.display();
}
}``````

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