MultiUserBalanceTransfer.java

package exp3;

public class MultiUserBalanceTransfer {

    public static void main(String[] args) {
        BankAccount bank = null;
        try {
            bank = new BankAccount(0);
        } catch (InvalidAmountException e) {
            System.err.println("[-] Failed to create bank account: " + e.getMessage());
            System.exit(1);
        }
        Customer customer1 = new Customer(
                bank,
                new double[]{100, 200, 300, 400, 500},
                new long[]{
                    // RandomDelayGenerator.generate(100, 1000),
                    // RandomDelayGenerator.generate(100, 1000),
                    // RandomDelayGenerator.generate(100, 1000),
                    // RandomDelayGenerator.generate(100, 1000),
                    // RandomDelayGenerator.generate(100, 1000)
                    100, 100, 100, 100, 100
                });
        Customer customer2 = new Customer(
                bank,
                new double[]{500, 400, 300, 200, 100},
                new long[] {
                // RandomDelayGenerator.generate(100, 1000),
                // RandomDelayGenerator.generate(100, 1000),
                // RandomDelayGenerator.generate(100, 1000),
                // RandomDelayGenerator.generate(100, 1000),
                // RandomDelayGenerator.generate(100, 1000)
                100, 100, 100, 100, 100
                });
        Thread thread1 = new Thread(customer1, "Customer-1");
        Thread thread2 = new Thread(customer2, "Customer-2");
        thread1.start();
        thread2.start();
    }
}

class WalletException extends Exception {

    public WalletException(String message) {
        super(message);
    }
}

class InvalidAmountException extends WalletException {

    public InvalidAmountException(String message) {
        super(message);
    }
}

class RandomDelayGenerator {

    public static long generate(long minDelay, long maxDelay) {
        return minDelay + (long) (Math.random() * (maxDelay - minDelay));
    }
}

class Customer implements Runnable {

    private BankAccount target;
    private double[] amounts; // 多次汇款的每次汇款金额
    private long[] delays; // 每次汇款的延迟时间

    public Customer(BankAccount target, double[] amounts, long[] delays) {
        this.target = target;
        this.amounts = amounts;
        this.delays = delays;
        System.out.println("[*] Customer " + Thread.currentThread().getName() + " is created with amounts: " + java.util.Arrays.toString(amounts) + " and delays: " + java.util.Arrays.toString(delays));
    }

    @Override
    public void run() {
        for (int idx = 0; idx < amounts.length; idx++) {
            double amount = amounts[idx];
            long delay = delays[idx];
            System.out.println("[*] Customer " + Thread.currentThread().getName() + " is transferring: " + amount);
            try {
                double newBalance = target.deposit(amount);
                System.out.println("[+] Customer " + Thread.currentThread().getName() + " transferred " + amount + ". New balance: " + newBalance);
            } catch (InvalidAmountException e) {
                System.err.println("[-] Failed to transfer amount " + amount + " with error: " + e.getMessage());
            }
            try {
                Thread.sleep(delay);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                System.err.println("[!] Thread interrupted while sleeping.");
            }
        }
    }
}

class BankAccount {

    private double balance;

    BankAccount(double balance) throws InvalidAmountException {
        if (balance < 0) {
            throw new InvalidAmountException("[!] Invalid account balance. Balance cannot be negative.");
        }
        this.balance = balance;
    }

    public double getBalance() {
        return balance;
    }

    public double deposit(double amount) throws InvalidAmountException {
        if (amount < 0) {
            throw new InvalidAmountException("[!] Invalid deposit amount. Amount cannot be negative.");
        }
        synchronized (this) {
            this.balance += amount;
        }
        return this.balance;
    }
}