Question

JAVA CODE

Write two definitions of a boolean method called equals(). The method compares the instance variables of the class for equality. One is in the Purchase class and the other is a static method of the main. Give sample calls for each.

public class PurchaseDemo

{ public static void main(String[] args)

{

Purchase oneSale = new Purchase();

oneSale.readInput();

oneSale.writeOutput();

System.out.println("Cost each $" + oneSale.getUnitCost());

System.out.println("Total cost $" + oneSale.getTotalCost());

}

}

import java.util.Scanner;
/**   
Class for the purchase of one kind of item, such as 3 oranges.
Prices are set supermarket style, such as 5 for $1.25.
*/
public class Purchase   
{
private String name;
private int groupCount; //Part of a price, like the 2 in //2 for $1.99.
private double groupPrice; //Part of a price, like the $1.99
// in 2 for $1.99.
private int numberBought; //Number of items bought.
public void setName(String newName)
{
name = newName;
}
/**   
Sets price to count pieces for $costForCount.   
For example, 2 for $1.99.   
*/
public void setPrice(int count, double costForCount)
{
if ((count <= 0) || (costForCount <= 0))
{
System.out.println("Error: Bad parameter in " +
"setPrice.");
System.exit(0);
}
else
{
groupCount = count;
groupPrice = costForCount;
}
}
public void setNumberBought(int number)
{
if (number <= 0)
{
System.out.println("Error: Bad parameter in " +
"setNumberBought.");
System.exit(0);
}
else
numberBought = number;
}
/**
Reads from keyboard the price and number of a purchase.
*/   
public void readInput()
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter name of item you are purchasing:");
name = keyboard.nextLine();
System.out.println("Enter price of item as two numbers.");
System.out.println("For example, 3 for $2.99 is entered as");
System.out.println("3 2.99");
System.out.println("Enter price of item as two numbers, " +
"now:");
groupCount = keyboard.nextInt();
groupPrice = keyboard.nextDouble();
while ((groupCount <= 0) || (groupPrice <= 0))
{ //Try again:
System.out.println("Both numbers must " +
"be positive. Try again.");
System.out.println("Enter price of " +
"item as two numbers.");
System.out.println("For example, 3 for " +
"$2.99 is entered as");
System.out.println("3 2.99");
System.out.println(
"Enter price of item as two numbers, now:");
groupCount = keyboard.nextInt();
groupPrice = keyboard.nextDouble();
}
System.out.println("Enter number of items purchased:");
numberBought = keyboard.nextInt();
while (numberBought <= 0)
{ //Try again:
System.out.println("Number must be positive. " +
"Try again.");
System.out.println("Enter number of items purchased:");
numberBought = keyboard.nextInt();
}
}
/**   
Displays price and number being purchased.
*/
public void writeOutput()   
{
System.out.println(numberBought + " " + name);
System.out.println("at " + groupCount +
" for $" + groupPrice);
}
public String getName()
{
return name;
}
public double getTotalCost()
{
return (groupPrice / groupCount) * numberBought;
}
public double getUnitCost()
{
return groupPrice / groupCount;
}
public int getNumberBought()
{
return numberBought;
}
}

Answer 1

Code

PurchaseDemo.java

public class PurchaseDemo
{
public static void main(String[] args)
{
Purchase oneSale1 = new Purchase();
Purchase oneSale2 = new Purchase();
oneSale1.readInput();
oneSale1.writeOutput();
oneSale2.readInput();
oneSale2.writeOutput();
if(oneSale1.equals(oneSale2))
System.out.println("Using Class level method:\nBoth are same");
else
System.out.println("Using Class level method:\nBoth are not same");
  
if(equals(oneSale1,oneSale2))
System.out.println("Using static method:\nBoth are same");
else
System.out.println("Using static method:\nBoth are not same");
//System.out.println("Cost each $" + oneSale.getUnitCost());
//System.out.println("Total cost $" + oneSale.getTotalCost());
}
public static boolean equals(Purchase obj1,Purchase obj2)
{
if (obj1 == null || obj1==null) {
return false;
}
if (obj1.getClass() != obj2.getClass()) {
return false;
}
if (!obj1.getName().equals(obj2.getName())) {
return false;
}
if (obj1.getNumberBought() != obj2.getNumberBought()) {
return false;
}
if (Double.doubleToLongBits(obj1.getUnitCost()) != Double.doubleToLongBits(obj2.getUnitCost())) {
return false;
}
return true;
}
}

Purchase .java class

import java.util.Objects;
import java.util.Scanner;
/**   
Class for the purchase of one kind of item, such as 3 oranges.
Prices are set supermarket style, such as 5 for $1.25.
*/
public class Purchase   
{
private String name;
private int groupCount; //Part of a price, like the 2 in //2 for $1.99.
private double groupPrice; //Part of a price, like the $1.99
// in 2 for $1.99.
private int numberBought; //Number of items bought.
public void setName(String newName)
{
name = newName;
}
/**   
Sets price to count pieces for $costForCount.   
For example, 2 for $1.99.   
*/
public void setPrice(int count, double costForCount)
{
if ((count <= 0) || (costForCount <= 0))
{
System.out.println("Error: Bad parameter in " +"setPrice.");
System.exit(0);
}
else
{
groupCount = count;
groupPrice = costForCount;
}
}
public void setNumberBought(int number)
{
if (number <= 0)
{
System.out.println("Error: Bad parameter in " +"setNumberBought.");
System.exit(0);
}
else
numberBought = number;
}
/**
Reads from keyboard the price and number of a purchase.
*/   
public void readInput()
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter name of item you are purchasing:");
name = keyboard.nextLine();
System.out.println("Enter price of item as two numbers.");
System.out.println("For example, 3 for $2.99 is entered as");
System.out.println("3 2.99");
System.out.println("Enter price of item as two numbers, " +"now:");
groupCount = keyboard.nextInt();
groupPrice = keyboard.nextDouble();
while ((groupCount <= 0) || (groupPrice <= 0))
{ //Try again:
System.out.println("Both numbers must " +"be positive. Try again.");
System.out.println("Enter price of " +"item as two numbers.");
System.out.println("For example, 3 for $2.99 is entered as");
System.out.println("3 2.99");
System.out.println(
"Enter price of item as two numbers, now:");
groupCount = keyboard.nextInt();
groupPrice = keyboard.nextDouble();
}
System.out.println("Enter number of items purchased:");
numberBought = keyboard.nextInt();
while (numberBought <= 0)
{ //Try again:
System.out.println("Number must be positive. " +
"Try again.");
System.out.println("Enter number of items purchased:");
numberBought = keyboard.nextInt();
}
}
/**   
Displays price and number being purchased.
*/
public void writeOutput()   
{
System.out.println(numberBought + " " + name);
System.out.println("at " + groupCount +
" for $" + groupPrice);
}
public String getName()
{
return name;
}
public double getTotalCost()
{
return (groupPrice / groupCount) * numberBought;
}
public double getUnitCost()
{
return groupPrice / groupCount;
}
public int getNumberBought()
{
return numberBought;
}

@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Purchase other = (Purchase) obj;
if (!Objects.equals(this.name, other.name)) {
return false;
}
if (this.groupCount != other.groupCount) {
return false;
}
if (Double.doubleToLongBits(this.groupPrice) != Double.doubleToLongBits(other.groupPrice)) {
return false;
}
return true;
}
  
}

output

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