面向对象（上）综合练习1：银行存取

账户  Account类

package day1_11.exer2;

//账户
public class Account {
    private double balance;//余额

    public Account(double balance) {
        this.balance = balance;
    }
    //获取余额
    public double getBalance() {
        return balance;
    }

    //存钱
    public void deposit(double amt) {
        if (amt > 0) {
            balance += amt;
            System.out.println("存入" + amt + "成功");
        }
    }

    //取钱
    public void withdraw(double amt) {
        if (balance > amt) {
            balance -= amt;
            System.out.println("取出" + amt + "成功");
        }else{
            System.out.println("取出" + amt + "失败");
        }
    }
}

客户 Customer类

package day1_11.exer2;
//客户
public class Customer {
    private String firstName;//名
    private String lastName;//姓
    private Account account;//账户

    public Customer(String f, String l) {
        this.firstName = f;
        this.lastName = l;
    }

    public Customer() {
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public Account getAccount() {
        return account;
    }

    public void setAccount(Account account) {
        this.account = account;
    }
}

银行 Bank类

package day1_11.exer2;

public class Bank {
    private Customer[] customers;//存放多个客户的数组
    private int numberOfCustomer;//记录客户的个数

    public Bank() {
        customers = new Customer[10];
    }

    //添加客户
    public void addCustomer(String f,String l) {
        Customer customer = new Customer(f, l);
        //customers[numberOfCustomer] = customer;
        //numberOfCustomer++;
        //简单写法
        customers[numberOfCustomer++] = customer;
    }

    //获取客户个数
    public int getNumberOfCustomer() {
        return numberOfCustomer;
    }

    //获取指定位置上的客户
    public Customer getCustomer(int index) {
        //return customers[index]   可能报异常
        if(index >= 0 && index <numberOfCustomer){
            return customers[index];
        }

        return null;
    }
}

测试 BankTest

package day1_11.exer2;

public class BankTest {
    public static void main(String[] args) {
        Bank bank = new Bank();
        bank.addCustomer("Davi", "Smith");
        //获取客户的个数
        int numberOfCustomer = bank.getNumberOfCustomer();
        System.out.println("客户个数：" + numberOfCustomer);
        //获取指定位置上的客户
        Customer customer = bank.getCustomer(numberOfCustomer-1);
        Account account = new Account(2000);
        customer.setAccount(account);
        //存钱100
        customer.getAccount().deposit(100);
        //查看余额
        System.out.println("客户：" + customer.getFirstName() + "的账户余额为：" + customer.getAccount().getBalance());
        //取钱2000
        customer.getAccount().withdraw(2000);
        //查看余额
        System.out.println("客户：" + customer.getFirstName() + "的账户余额为：" + customer.getAccount().getBalance());

        System.out.println("**********************");

        bank.addCustomer("慕容","上官");
        System.out.println("客户个数：" + bank.getNumberOfCustomer());
        Customer customer2 = bank.getCustomer(bank.getNumberOfCustomer() - 1);
        customer2.setAccount(new Account(100));
        //存100
        customer2.getAccount().deposit(100);
        //查看余额
        System.out.println("客户：" + customer2.getFirstName() + "的账户余额为：" + customer2.getAccount().getBalance());
        //取300
        customer2.getAccount().withdraw(3000);
        //查看余额
        System.out.println("客户：" + customer2.getFirstName() + "的账户余额为：" + customer2.getAccount().getBalance());
    }
}

运行结果