In Java, a TreeMap is part of the java.util package and implements the NavigableMap interface. It stores key-value pairs in a sorted order based on the keys. A common use case of TreeMap is to store account balances of customers, where the account balance is the key, and the account holder or other information is the value. You can then use this…

InterestCalculation.java

import java.util.Map;
import java.util.TreeMap;

public class InterestCalculation {
    public static void main(String[] args) {
        // Creating a TreeMap to store account balances sorted by balance
        TreeMap<Double, String> accountBalances = new TreeMap<>();
        
        // Adding account balances and account holder names
        accountBalances.put(5000.00, "John Doe");
        accountBalances.put(15000.00, "Jane Smith");
        accountBalances.put(3000.00, "Alice Johnson");
        accountBalances.put(25000.00, "Bob Brown");
        accountBalances.put(12000.00, "Charlie Davis");

        // Print header for the interest report
        System.out.println("Account Balance Interest Report");
        System.out.println("--------------------------------");
        
        // Iterate through the TreeMap and calculate interest on each balance
        for (Map.Entry<Double, String> entry : accountBalances.entrySet()) {
            Double balance = entry.getKey();
            String accountHolder = entry.getValue();
            
            // Calculate interest based on balance
            double interestRate = getInterestRate(balance);
            double interest = balance * interestRate;

            // Print the account holder, balance, interest rate, and interest
            System.out.printf("Account Holder: %-15s | Balance: $%-10.2f | Interest: $%-10.2f | Rate: %.2f%%\n",
                    accountHolder, balance, interest, interestRate * 100);
        }
    }

    // Method to determine interest rate based on balance
    public static double getInterestRate(double balance) {
        if (balance < 5000) {
            return 0.01;  // 1% interest for balances below $5000
        } else if (balance < 10000) {
            return 0.02;  // 2% interest for balances between $5000 and $9999
        } else if (balance < 20000) {
            return 0.03;  // 3% interest for balances between $10000 and $19999
        } else {
            return 0.04;  // 4% interest for balances over $20000
        }
    }
}

Key Points:
Sorted by Balance: Since TreeMap stores keys in sorted order, the account balances are displayed in ascending order.
Interest Calculation: The method getInterestRate() determines the interest rate based on the balance, making it easy to adjust interest rules as needed.
Formatting Output: The System.out.printf() function is used to display a nicely formatted report.