简易银行系统

/*
 * Solution using Java Stream
 * The Bank class simulates a simple banking system with functionalities for transferring, depositing, and withdrawing money.
 * In this solution, we use Java Streams for more functional-style processing.
 */
import java.util.Arrays;
import java.util.stream.IntStream;

public class Bank {
    private long[] balance;

    public Bank(long[] balance) {
        this.balance = Arrays.copyOf(balance, balance.length);
    }

    public boolean transfer(int account1, int account2, long money) {
        // Check if both accounts are valid and if account1 has enough balance
        return isValidAccount(account1) && isValidAccount(account2) && balance[account1 - 1] >= money
                && IntStream.of(account1 - 1, account2 - 1)
                           .filter(i -> i >= 0 && i < balance.length)
                           .reduce((acc1, acc2) -> {
                               balance[acc1] -= money;
                               balance[acc2] += money;
                               return acc2;
                           })
                           .isPresent();
    }

    public boolean deposit(int account, long money) {
        // Check if the account is valid
        return isValidAccount(account) && updateBalance(account - 1, money, true);
    }

    public boolean withdraw(int account, long money) {
        // Check if the account is valid and has enough balance
        return isValidAccount(account) && updateBalance(account - 1, money, false);
    }

    private boolean isValidAccount(int account) {
        return account > 0 && account <= balance.length;
    }

    private boolean updateBalance(int account, long money, boolean deposit) {
        if (deposit) {
            balance[account] += money;
        } else if (balance[account] >= money) {
            balance[account] -= money;
            return true;
        }
        return deposit;
    }
}