java：多线程实现银行ATM机，要求有存款机，取款机和存取款一体机三种类型的机器；每一种机器至少有两个用户使用。

好的，下面是一个简单的 Java 多线程实现银行 ATM 机的示例代码：

// 存款机类
class DepositMachine implements Runnable {
    private Bank bank;
    private String name;

    public DepositMachine(Bank bank, String name) {
        this.bank = bank;
        this.name = name;
    }

    public void run() {
        while (true) {
            int amount = (int) (Math.random() * 1000);
            bank.deposit(name, amount);
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

// 取款机类
class WithdrawMachine implements Runnable {
    private Bank bank;
    private String name;

    public WithdrawMachine(Bank bank, String name) {
        this.bank = bank;
        this.name = name;
    }

    public void run() {
        while (true) {
            int amount = (int) (Math.random() * 1000);
            bank.withdraw(name, amount);
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

// 存取款一体机类
class ATM implements Runnable {
    private Bank bank;
    private String name;

    public ATM(Bank bank, String name) {
        this.bank = bank;
        this.name = name;
    }

    public void run() {
        while (true) {
            int amount = (int) (Math.random() * 1000);
            if (Math.random() < 0.5) {
                bank.deposit(name, amount);
            } else {
                bank.withdraw(name, amount);
            }
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

// 银行类
class Bank {
    private Map<String, Integer> accounts;

    public Bank() {
        accounts = new HashMap<String, Integer>();
        accounts.put("Alice", 1000);
        accounts.put("Bob", 2000);
        accounts.put("Charlie", 3000);
    }

    public synchronized void deposit(String name, int amount) {
        int balance = accounts.get(name);
        balance += amount;
        accounts.put(name, balance);
        System.out.println(name + " deposited " + amount + ", balance is " + balance);
    }

    public synchronized void withdraw(String name, int amount) {
        int balance = accounts.get(name);
        if (balance < amount) {
            System.out.println(name + " tried to withdraw " + amount + ", but balance is not enough");
            return;
        }
        balance -= amount;
        accounts.put(name, balance);
        System.out.println(name + " withdrew " + amount + ", balance is " + balance);
    }
}

// 测试类
public class BankTest {
    public static void main(String[] args) {
        Bank bank = new Bank();
        Thread[] threads = new Thread[6];
        threads[0] = new Thread(new DepositMachine(bank, "Alice"));
        threads[1] = new Thread(new DepositMachine(bank, "Bob"));
        threads[2] = new Thread(new WithdrawMachine(bank, "Alice"));
        threads[3] = new Thread(new WithdrawMachine(bank, "Bob"));
        threads[4] = new Thread(new ATM(bank, "Charlie"));
        threads[5] = new Thread(new ATM(bank, "Charlie"));
        for (int i = 0; i < 6; i++) {
            threads[i].start();
        }
    }
}

上面的代码定义了三个类：`DepositMachine` 表示存款机，`WithdrawMachine` 表示取款机，`ATM` 表示存取款一体机；还有一个 `Bank` 类表示银行。在 `DepositMachine`、`WithdrawMachine` 和 `ATM` 类中，都实现了 `Runnable` 接口，并且在 `run` 方法中模拟了用户进行存款、取款或存取款操作。在 `Bank` 类中，使用了一个 `Map` 来存储每个用户的账户余额，并且实现了 `deposit` 和 `withdraw` 方法来处理存款和取款操作，同时使用了 `synchronized` 关键字来保证线程安全。

在测试类 `BankTest` 中，创建了 6 个线程，其中前两个线程分别表示 Alice 和 Bob 使用存款机进行存款，第三个和第四个线程表示 Alice 和 Bob 使用取款机进行取款，最后两个线程表示 Charlie 使用存取款一体机进行存取款操作。运行程序后，可以看到多个线程同时对银行账户进行操作，但是由于使用了 `synchronized` 关键字，所以不会出现线程安全问题。