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/**
* Assignment 2, COMP268 Class: CreditCard.java
*
* @description Provides an implementation of Luhn's algorithm
* @author: mo khan Student ID: 3431709
* @date Jun 9, 2019
* @version 1.0
*/
package Q3;
import java.util.*;
public class CreditCard {
private int evenSum = 0;
private int oddSum = 0;
private int sum = 0;
private String ccNumber;
private String company;
public CreditCard(String num) {
this.ccNumber = num;
this.company = this.identifyCompany(num);
this.calculateSums(num);
}
/**
* Returns the sum of the even digits
*
* @return the sum of the even digits
*/
public int getEvenSum() {
return evenSum;
}
/**
* Returns the sum of the odd digits
*
* @return the sum of the odd digits
*/
public int getOddSum() {
return oddSum;
}
/**
* Returns the sum of all the digits
*
* @return the sum of the even and odd digits.
*/
public int getSum() {
return sum;
}
/**
* Return the credit card number
*
* @return the credit card number.
*/
public String getCcNumber() {
return this.ccNumber;
}
/**
* Return the company that issues this credit card number.
*
* @return the name of the company that owns this credit card number.
*/
public String getCompany() {
return this.company;
}
/** @return true if the credit card # is valid, otherwise returns false. */
public boolean isValid() {
return this.validateCompany()
&& this.validateLength()
&& this.validateNumber()
&& this.validateSums()
&& this.isDivisibleBy10();
}
/** @return true if the total sum is divisible by 10, otherwise returns false. */
public boolean isDivisibleBy10() {
return ((this.getSum()) % 10) == 0;
}
/**
* Validates the company that the credit card number belongs to.
*
* @return true if the card belongs to one of the described credit card company, otherwise false.
*/
public boolean validateCompany() {
return this.ccNumber.startsWith("4")
|| this.ccNumber.startsWith("5")
|| this.ccNumber.startsWith("37")
|| this.ccNumber.startsWith("6");
}
/** @return true if the length of the card number is valid. */
public boolean validateLength() {
return this.ccNumber.length() >= 13 && this.ccNumber.length() <= 16;
}
/** @return true if each character in the credit card number is a digit. */
public boolean validateNumber() {
for (int i = 0; i < this.ccNumber.length(); i++)
if (!Character.isDigit(this.ccNumber.charAt(i))) return false;
return true;
}
/** @return true if the sum is greater than 0; */
public boolean validateSums() {
return this.evenSum > 0 && this.oddSum > 0;
}
private String identifyCompany(String number) {
if (validateCompany())
switch (number.charAt(0)) {
case '3':
return "American Express";
case '4':
return "Visa";
case '5':
return "MasterCard";
case '6':
return "Discover";
}
return "Unknown";
}
private void calculateSums(String number) {
if (!validateNumber()) return;
String reversed = this.reverseString(number);
for (int i = 0; i < reversed.length(); i++) {
int digit = this.digitFrom(reversed, i);
if (this.isOdd(i + 1)) this.oddSum += digit;
else {
String value = String.valueOf(digit * 2);
for (int j = 0; j < value.length(); j++) this.evenSum += this.digitFrom(value, j);
}
}
this.sum = this.oddSum + this.evenSum;
}
private String reverseString(String value) {
return new StringBuilder(value).reverse().toString();
}
private boolean isEven(int number) {
return number % 2 == 0;
}
private boolean isOdd(int number) {
return !this.isEven(number);
}
private int digitFrom(String input, int index) {
return Character.getNumericValue(input.charAt(index));
}
/**
* The entry point to the console application.
*
* @param args the argument vector provided to the console application.
*/
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("Enter credit card #:");
CreditCard creditCard = new CreditCard(in.next());
if (creditCard.isValid())
System.out.println(
String.format("%s is offerred by %s", creditCard.getCcNumber(), creditCard.getCompany()));
else System.out.println(String.format("%s in invalid", creditCard.getCcNumber()));
}
}
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