Java 小案例+super使用

 1 package com.bytezero.supertest3;
 2
 3 /**
 4  *
 5  * @Description    AccountTest类
 6  * @author  Bytezero·zhenglei!      Email:420498246@qq.com
 7  * @version
 8  * @date 2021年9月20日上午9:52:27
 9  * @
10  *
11  */
12 public class AccountTest
13 {
14     public static void main(String[] args) {
15
16         Account acct = new Account(1122,20000,0.045);
17
18         acct.withdraw(30000);
19         System.out.println("您的账户余额为："+acct.getBalance());
20
21         acct.withdraw(2500);
22         System.out.println("您的账户余额为："+acct.getBalance());
23
24         acct.deposit(3000);
25         System.out.println("您的账户余额为："+acct.getBalance());
26
27         System.out.println("月利率为："+(acct.getMonthlyInterest() *100) +"%");
28
29
30
31     }
32 }

 1 package com.bytezero.supertest3;
 2
 3 public class Account
 4 {
 5     private int id;           //账号
 6     private double balance;   //余额
 7     private double annualInterestRate;   //年利率
 8
 9     //构造器
10     public Account(int id, double balance, double annualInterestRate)
11     {
12         super();
13         this.id = id;
14         this.balance = balance;
15         this.annualInterestRate = annualInterestRate;
16     }
17
18     //get  set
19
20     public int getId()
21     {
22         return id;
23     }
24     public void setId(int id)
25     {
26         this.id = id;
27     }
28
29     public double getBalance()
30     {
31         return balance;
32     }
33
34     public void setBalance(double balance)
35     {
36         this.balance = balance;
37     }
38
39     public double getAnnualInterestRate()
40     {
41         return annualInterestRate;
42     }
43
44     public void setAnnualInterestRate(double annualInterestRate)
45     {
46         this.annualInterestRate = annualInterestRate;
47     }
48
49     //返回月利率
50     public double getMonthlyInterest()
51     {
52         return annualInterestRate / 12;
53     }
54
55     //取钱
56     public void withdraw(double amount)
57     {
58         if(balance >= amount)
59         {
60             balance -= amount;
61             return;
62         }
63         System.out.println("余额不足！");
64     }
65
66
67     //存钱
68     public void deposit(double amount)
69     {
70         if(amount > 0)
71         {
72             balance += amount;
73         }
74
75
76
77
78
79     }
80
81
82
83
84 }

 1 package com.bytezero.supertest3;
 2
 3 /**
 4  *
 5  * @Description
 6  * @author  Bytezero·zhenglei!      Email:420498246@qq.com
 7  * @version
 8  * @date 2021年9月20日上午11:08:11
 9  * @
10  *
11  */
12 public class CheckAccountTest
13 {
14     public static void main(String[] args)
15     {
16         CheckAccount acct = new CheckAccount(1122,20000,0.045,5000);
17
18         acct.withdraw(5000);
19         System.out.println("您的账户余额为："+ acct.getBalance());
20         System.out.println("您的可透支额度为："+acct.getOverdraft());
21
22         acct.withdraw(18000);
23         System.out.println("您的账户余额为："+ acct.getBalance());
24         System.out.println("您的可透支额度为："+acct.getOverdraft());
25
26         acct.withdraw(3000);
27         System.out.println("您的账户余额为："+ acct.getBalance());
28         System.out.println("您的可透支额度为："+acct.getOverdraft());
29
30
31
32
33     }
34 }

 1 package com.bytezero.supertest3;
 2
 3 /*
 4  *
 5  *
 6  */
 7 public class CheckAccount extends Account
 8 {
 9     private double overdraft; //可透支的限额
10
11
12
13     public CheckAccount(int id, double balance, double annualInterestRate,double overdraft)
14     {
15         super(id, balance, annualInterestRate);
16         this.overdraft = overdraft;
17     }
18
19
20
21
22     public double getOverdraft() {
23         return overdraft;
24     }
25
26
27
28
29     public void setOverdraft(double overdraft) {
30         this.overdraft = overdraft;
31     }
32
33
34
35
36     @Override
37     public void withdraw(double amount)
38     {
39         if(getBalance() >= amount)  //余额足够
40         {
41             //方式一
42             //setBalance(getBalance() - amount);
43
44             //方式二
45             super.withdraw(amount);
46             //方式三
47             //可以将父类的 private double balance;   //余额 改为
48                          //protected double balance
49
50
51
52         }
53         //余额不够   透支额度 + 余额消费
54         else if(overdraft >=( amount - getBalance()))
55         {
56             overdraft -= (amount - getBalance());
57
58             //setBalance(0);
59             //或者
60             super.withdraw(getBalance());
61
62         }
63         else
64         {
65             System.out.println("超过可透支限额！");
66         }
67
68     }
69
70
71
72
73
74
75 }