面向对象的练习1：Account_Customer_Bank

1.创建Account类

public class Account {
      private double balance;
      //constructor
      public Account(double init_balance){
    	  this.balance=init_balance;
      }
      //method
	public double getBalance() {
		return balance;
	}
	//存款
      public void deposit(double amt){
    	    	  System.out.println("成功存款："+amt);
    	    	  balance+=amt;
      }
      //取款
      public void withdraw(double amt){
    	  if(balance>=amt){
    		  balance-=amt;
    	  System.out.println("成功取款："+amt);
    	  }else{
    		  System.out.println("余额不足");
    	  }
       }
      
}

2.创建Customer类 

public class Customer {
       private String firstName;
       private String lastName;
       private Account account;
       //constructor
       public Customer(String f,String l){
    	   this.firstName=f;
    	   this.lastName=l;
       }
       //method
	public Account getAccount() {
		return account;
	}
	public void setAccount(Account account) {
		this.account = account;
	}
	public String getFirstName() {
		return firstName;
	}
	public String getLastName() {
		return lastName;
	}
       
}

3.创建Bank类

public class Bank {
     private Customer[] customers;//存放多个客户
     private int numberOfCustomer;//记录客户的个数
     //constructor
     public Bank(){
    	 customers=new Customer[10];
     }
     //method
     //添加客户
     public void addCustomer(String f,String l){
    	 Customer cust=new Customer(f,l);
    	 customers[numberOfCustomer]=cust;
    	 numberOfCustomer++;
     }
     //获取指定索引位置上的客户
	public Customer getCustomer(int index) {
		if(index>=0 && index<numberOfCustomer){
		return customers[index];
		}else{
			return null;
		}
	}
	//获取客户的个数
	public int getNumberOfCustomer() {
		return numberOfCustomer;
	}
     
}

4.创建 BankTest类，进行测试。 

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().deposit(2000);
    	 System.out.println("客户："+bank.getCustomer(0).getFirstName()+"账户余额为："+bank.getCustomer(0).getAccount().getBalance());
         bank.addCustomer("amy", "me");
         System.out.println("银行的客户个数为："+bank.getNumberOfCustomer());
         bank.getCustomer(1).setAccount(new Account(1000));
         bank.getCustomer(1).getAccount().withdraw(11111);
         
         
      }
}

5.BankTest测试结果