Java Program Calculates Balance on Credit Card

Introduction

Calculating the balance on a credit card after interest is a common financial calculation. This is typically done when you want to determine how much you'll owe after a certain period with compound interest. The calculation involves applying the interest rate to the current balance over a specified number of periods.

In this guide, we'll create a Java program that performs this calculation. The program will take the current balance, annual interest rate, and number of months as inputs, then output the new balance after interest has been applied.

Formula

The formula for calculating the new credit card balance after interest is:

Where:

• Current Balance is the amount currently owed on the credit card
• Annual Interest Rate is the interest rate percentage per year
• Number of Months is the period over which the interest is applied

This formula calculates the balance using compound interest, where the interest is applied to the current balance each month.

Java Program

Here's a complete Java program that implements the credit card balance calculation:

import java.util.Scanner;

public class CreditCardBalanceCalculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Get input values
        System.out.print("Enter current balance: ");
        double currentBalance = scanner.nextDouble();

        System.out.print("Enter annual interest rate (in %): ");
        double annualInterestRate = scanner.nextDouble();

        System.out.print("Enter number of months: ");
        int months = scanner.nextInt();

        // Calculate new balance
        double monthlyInterestRate = annualInterestRate / 12 / 100;
        double newBalance = currentBalance * Math.pow(1 + monthlyInterestRate, months);

        // Display result
        System.out.printf("New balance after %d months: $%.2f%n", months, newBalance);

        scanner.close();
    }
}

The program uses the Scanner class to get user input for the current balance, annual interest rate, and number of months. It then calculates the new balance using the formula and displays the result.

Example Calculation

Let's walk through an example to see how the calculation works. Suppose you have a credit card with:

• Current Balance: $1,000
• Annual Interest Rate: 18%
• Number of Months: 6

Using the formula:

So, after 6 months with an 18% annual interest rate, the new balance would be $1,091.60.