JAVA---练习

有以下UML类图

Account类

package exer;

public class Account {
	//余额
	private double balance;
	//构造器
	public Account(double init_balance){
		this.balance=init_balance;
	}
	//获取余额
	public double getBalance(){
		return balance;
	}
	//存款
	public void deposit(double amt){
		if(amt>0){
			balance+=amt;
			System.out.println("存钱成功！存了"+amt+"元！");
		}
	}
	//取款
	public void withdraw(double amt){
		if(balance>=amt){
			balance-=amt;
			System.out.println("取款成功！取走了"+amt+"元！");
		}
		else{
			System.out.println("余额不足！");
		}
	}
}

Customer类

package exer;

public class Customer {
	//姓
	private String firstName;
	//名
	private String lastName;
	//账户
	private Account account;
	
	//构造器
	public Customer(String f,String l){
		this.firstName=f;
		this.lastName=l;
	}
	
	public String getFirstName(){
		return firstName;
	}
	public String getLastName(){
		return lastName;
	}
	public Account getAccount(){
		return account;
	}
	public void setAccount(Account acct){
		this.account=acct;
	}
	
}

Bank类

package exer;

public class Bank {
	private Customer[] customers;
	int numberOfCustomer;
	
	public Bank(){
		customers=new Customer[10];
	}
	public void addCustomer(String f,String l){
		Customer cust=new Customer(f,l);
		customers[numberOfCustomer++]=cust;
	}
	public int getNumOfCustomers(){
		return numberOfCustomer;
	}
	public Customer getCustomer(int index){
		if(index>=0&&index<this.numberOfCustomer){
			return customers[index];
		}
		return null;
	}
	
}

BankTest类

package exer;

public class BankTest {
	public static void main(String[] args) {
		Bank bank=new Bank();
		bank.addCustomer("Jane","Smith");
		bank.getCustomer(0).setAccount(new Account(2000));
		bank.getCustomer(0).getAccount().withdraw(500);
		double balance = bank.getCustomer(0).getAccount().getBalance();
		System.out.println("客户："+bank.getCustomer(0).getFirstName()+"的账户余额为："+balance);
		System.out.println("*******************");
		bank.addCustomer("三", "张");
		int numOfCustomers = bank.getNumOfCustomers();
		System.out.println(numOfCustomers);
	}
}