Java Interface: Banking system classes - Bank Account, Savings Account, and Current Account

Java Interface: Exercise-4 with Solution

Write a Java programming to create a banking system with three classes - Bank, Account, SavingsAccount, and CurrentAccount. The bank should have a list of accounts and methods for adding them. Accounts should be an interface with methods to deposit, withdraw, calculate interest, and view balances. SavingsAccount and CurrentAccount should implement the Account interface and have their own unique methods.

Sample Solution:

Java Code:

// Account.java
// Interface Account

interface Account {
    void deposit(double amount);
    void withdraw(double amount);
    double getBalance();
}

// SavingsAccount.java
// Class SavingsAccount

class SavingsAccount implements Account {
    private double balance;
    private double interestRate;

    public SavingsAccount(double initialDeposit, double interestRate) {
        this.balance = initialDeposit;
        this.interestRate = interestRate;
    }

    @Override
    public void deposit(double amount) {
        balance += amount;
    }

    @Override
    public void withdraw(double amount) {
        balance -= amount;
    }

    @Override
    public double getBalance() {
        return balance;
    }
   
    // Applying interest rate 1.25% for 1 year: 
    public void applyInterest() {
        balance += balance * interestRate/100;
    }
}

// CurrentAccount.java
// Class CurrentAccount

class CurrentAccount implements Account {
    private double balance;
    private double overdraftLimit;

    public CurrentAccount(double initialDeposit, double overdraftLimit) {
        this.balance = initialDeposit;
        this.overdraftLimit = overdraftLimit;
    }

    @Override
    public void deposit(double amount) {
        balance += amount;
    }

    @Override
    public void withdraw(double amount) {
        if (balance + overdraftLimit >= amount) {
            balance -= amount;
        }
    }

    @Override
    public double getBalance() {
        return balance;
    }

    public void setOverdraftLimit(double overdraftLimit) {
        this.overdraftLimit = overdraftLimit;
    }
}

// Bank.java
// Class Bank
import java.util.ArrayList;
import java.util.List;

class Bank {
    private List accounts;

    public Bank() {
        accounts = new ArrayList<>();
    }

    public void addAccount(Account account) {
        accounts.add(account);
    }

    public void removeAccount(Account account) {
        accounts.remove(account);
    }

    public void deposit(Account account, double amount) {
        account.deposit(amount);
    }

    public void withdraw(Account account, double amount) {
        account.withdraw(amount);
    }

    public void printAccountBalances() {
        for (Account account : accounts) {
            System.out.println("Account balance: " + account.getBalance());
        }
    }
}

// Main.java
// Class Main

public class Main {
    public static void main(String[] args) {
        Bank bank = new Bank();
        SavingsAccount savingsAccount = new SavingsAccount(1000.0, 1.25);
        System.out.println("Savings Account:\nInitial Deposit: $1000.00\nInterest rate: 1.25%");  
        CurrentAccount currentAccount = new CurrentAccount(5000.0, 1000.0);
        System.out.println("\nCurrent Account:\nInitial Deposit: $5000.00\nOverdraftLimit: $1000.00");
		bank.addAccount(savingsAccount);
        bank.addAccount(currentAccount);
		System.out.println("\nNow deposit $100 to Savings Account.");
        bank.deposit(savingsAccount, 100.0);
        System.out.println("Now deposit $500 to Current Account.");
		bank.deposit(currentAccount, 500.0);	
		System.out.println("Withdraw $150 from Savings Account.\n");
        bank.withdraw(savingsAccount, 150.0);
        System.out.println("\nSavings A/c and Current A/c.:");
		bank.printAccountBalances();
        savingsAccount.applyInterest();
        System.out.println("\nAfter applying interest on Savings A/c for 1 year:");
		System.out.println("Savings A/c and Current A/c.:");
        bank.printAccountBalances();
    }
}

Sample Output:

Savings Account:
Initial Deposit: $1000.00
Interest rate: 1.25%

Current Account:
Initial Deposit: $5000.00
OverdraftLimit: $1000.00

Now deposit $100 to Savings Account.
Now deposit $500 to Current Account.
Withdraw $150 from Savings Account.


Savings A/c and Current A/c.:
Account balance: 950.0
Account balance: 5500.0

After applying interest on Savings A/c for 1 year:
Savings A/c and Current A/c.:
Account balance: 961.875
Account balance: 5500.0

Flowchart of Interface Account:

Flowchart of Class SavingsAccount:

Flowchart of Class CurrentAccount:

Flowchart of Class Bank:

Flowchart of Class Main:

Java Code Editor:

Contribute your code and comments through Disqus.

Previous: Implement the Flyable interface.