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问OOP ATM实现
EN

Code Review用户

提问于 2021-05-08 12:36:29

回答 1查看 220关注 0票数 0

我试图以面向对象的方式体现一些基本的ATM操作，以供实践。会喜欢从结构，面向对象的原则的一些评论指针。另外，为了更好地掌握OO设计，我下一步应该做些什么(我想读更多的代码而不是书籍/视频，已经把我的思想从5年的教程中推出来了)。

假设--我的ATM实现包括创建一个用户并从一个ATM上打开一个银行帐户。

自动取款机业务-

帐户类别

开户
核对平衡
撤走
引脚更换
迷你声明

package templates;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Account {

    private long accountBalance;
    private List miniStatement;
    private boolean accountStatus;
    private String accountPIN;
    
    public Account() {
        
        this.accountBalance = 10000;
        this.accountStatus = true;
        this.accountPIN = "1111";   
        this.miniStatement = new ArrayList<>();
        
    }
    
    public String doWithdraw(long amount) {
        
        if(this.accountStatus) {
            if(getBalance() > 0.00 && amount > 0.00 && getBalance() >= amount) {
                
                this.accountBalance -= amount;
                String str =  "Account debited with $"+amount;
                this.miniStatement.add(str);
                return str;
                
            }else
                return "Amount entered is high, please enter less amount !!! "; 
        }else
            return "Account is already closed"; 
                
    }
    
    public double getBalance() {
        
        if(checkAccountStatus())
            return this.accountBalance;
        return -1.00;
    }
    
    public boolean changePIN(String newPin) {
        
        if(checkAccountStatus()) {
            this.accountPIN = newPin;
            return true;
        }
        return false;
    }
    
    private boolean checkAccountStatus() {
        return this.accountStatus;
    }
    
    public String closeAccount() {
    
        if(checkAccountStatus()) {
            
            String str = "Please collect $"+ getBalance();
    
            this.accountStatus = false;
            
            return str+". Account is now closed";
        }
        return "Account is already closed";
        
    }
    
    public Iterator printMiniStatement() {
        
        return this.miniStatement.iterator();
            
    }
        
}

用户类

创建用户
设置名
取名
设置姓
取得姓
设置用户地址
获取用户地址
设定电话号码
弄到电话号码

package templates;

public class User {

    private String firstName;
    private String lastName;
    private String address;
    private String phoneNumber;
    
    public User(String firstName,String lastName,String address,String phoneNumber) {
        
        this.firstName = firstName;
        this.lastName = lastName;
        this.address = address;
        this.phoneNumber = phoneNumber;
        
    }
    
    public void setFirstName(String fname) {

        this.firstName = fname;     
    }

    public String getFirstName() {
        return this.firstName;
    }
    
    public void setLastName(String lname) {
        
        this.lastName = lname;
        
    }

    public String getLastName() {
        return this.lastName;
    }
    
    public void setAddress(String addr) {
        
        this.address = addr;
        
    }

    public String getAddress() {
        return this.address;
    }
    
    public void setPhoneNumer(String phonenum) {
        
        this.phoneNumber = phonenum;
        
    }

    public String getPhoneNumber() {
        return this.phoneNumber;
    }
}

主/测试类

package test;

import java.util.Iterator;

import templates.*;

public class ATMTest {

    public static void main(String[] args) {
        
        Account savings = new Account();
        
        User user1 = new User("Dummy","Name","27, First Floor, Suok-I","8888888888");
        
        System.out.printf("%s%n", "Account Balance is $"+savings.getBalance());
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", savings.doWithdraw(50));
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", savings.doWithdraw(5540));
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", savings.doWithdraw(3350));
        
        System.out.println("-------------------------------------");        
        
        System.out.printf("%s%n", savings.doWithdraw(1090));
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", savings.doWithdraw(90));
        
        System.out.println("-------------------------------------");

        System.out.printf("%s%n", savings.doWithdraw(966));
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", "Account Balance is $"+savings.getBalance());
        
        System.out.println("-------------------------------------");
        
        savings.changePIN("1611");
        
        Iterator itr = savings.printMiniStatement();
        
        System.out.printf("%20s%n", "MINI STATEMENT");
        
        while(itr.hasNext()) {
            
            System.out.printf("%s%n", itr.next());
            
        }
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", user1.getFirstName());
        
        System.out.printf("%s%n", user1.getLastName());
        
        System.out.printf("%s%n", user1.getAddress());
        
        System.out.printf("%s%n", user1.getPhoneNumber());
        
        System.out.println("-------------------------------------");
        
        user1.setFirstName("Rain");
        
        user1.setLastName("Man");
        
        user1.setAddress("32, Second Floor, Suok-I");
        
        user1.setPhoneNumer("9999999999");
        
        System.out.printf("%s%n", user1.getFirstName());
        
        System.out.printf("%s%n", user1.getLastName());
        
        System.out.printf("%s%n", user1.getAddress());
        
        System.out.printf("%s%n", user1.getPhoneNumber());
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", savings.closeAccount());
        
        System.out.println("-------------------------------------");
        
        System.out.printf("%s%n", savings.doWithdraw(1111));
        
        System.out.println("-------------------------------------");
    }

}

java

object-oriented

回答 1

Code Review用户

发布于 2021-05-11 18:05:53

只提交可编译代码以检查

您的ATMTest中有一个类型问题。printMiniStatement-Method in Iterator itr = savings.printMiniStatement();有返回类型void，但是变量需要一个Iterator。因此，代码无法编译。

逻辑与设计

您应该介绍一些用户和帐户之间的关系，因为它们显然是相互关联的。例如：

用户可能有几个帐户:您可以将字段List accounts添加到User
一个帐户只有一个用户:您可以将字段User user添加到Account

您应该添加一个ATM-Class，它负责执行撤回操作。这不应由帐户本身来完成。要了解更多信息，请看一下单一责任原则(下面的链接)。您还应该向帐户中添加一个字段String id。它可以与accountPin-field结合使用，以允许ATM实例进行某种身份验证。

正如吉尔伯特所指出的:在代表货币时不要使用浮点数。浮点表示不能100%准确，因此有时会丢失/添加几美分。使用整数/长代替。它们不会受到精确错误的影响，也不会导致这些很难确定的错误类型(下面的链接)。

以及为什么Account-Class只有一个指定任意值的无参数构造函数？

Further阅读：

单一责任原则：https://stackify.com/solid-design-principles/
浮点精度误差：https://www.simplexacode.ch/en/blog/2018/07/using-bigdecimal-as-an-accurate-replacement-for-floating-point-numbers/

toString-Method

您可以重写类‘toString-Method’，以便System.out.println(...)可以推断其实例的字符串表示形式。以下面的场景为例:创建一个新用户并立即打印出指定的值。在您的ATMTest-class中，您只是通过反复调用不同的getter来做到这一点。通过重写用户的"toString"-Method，可以将其缩写为：System.out.println(new User(...))

Further阅读：

https://www.baeldung.com/java-tostring

this-keyword

只有在必须避免模糊/模糊的情况下才使用this。否则，它会使您的代码更难阅读。

Further阅读：

何时使用this：https://docs.oracle.com/javase/tutorial/java/javaOO/thiskey.html
阴影教程：https://javabeginnerstutorial.com/core-java-tutorial/variable-shadowing/

白色空间

使用白空间对您有利。在阅读某人的代码时，由空格创建的视觉空白是必要的指南。它们提供了额外的结构，从而提高了可读性。

Further阅读：

代码-约定：https://www.oracle.com/java/technologies/javase/codeconventions-whitespace.html

Wildcard-Import

像import templates.*;这样的语句导入templates-package中的所有类。避免通配符-导入，因为它们可能导致麻烦的错误，当编译时，由于命名冲突。

Further阅读：

https://stackoverflow.com/questions/147454/why-is-using-a-wild-card-with-a-java-import-statement-bad

我只向您的代码标记点添加了几个注释，在这些地方可以实现上述点。Account类的运行方式与以前一样

package templates;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Account {
    /*
    "accountBalance" can be renamed to "balance" since "accountBalance" always belongs to an instance of "Account".
    Preceding "Balance" by "account" doesn't add any information
    */
    private double accountBalance;
    private List miniStatement;
    /*
    "accountStatus" is an extremly broad term and may lead to confusion. If your goal was to mark an account as closed
    consider renaming "accountStatus" to "isClosed"
    */
    private boolean accountStatus;
    private String accountPIN;

    public Account() {
        /*
        the "this"-keyword is only required if you need to avoid ambiguity (this applies to most of your getters/setters as well!!)
        take a look at your "User"-Constructor for more information (I left another comment over there :) )
         */

        this.accountBalance = 10000.0;
        this.accountStatus = true;
        this.accountPIN = "1111";
        this.miniStatement = new ArrayList<>();

    }


    public String doWithdraw(double amount) {
        // Consistency! use either "this.accountStatus" or "checkAccountStatus()"
        if(this.accountStatus) {
            if(getBalance() > 0.00 && amount > 0.00 && getBalance() >= amount) {

                this.accountBalance -= amount;
                // use meaningful names e.g. "substatement"
                String str =  "Account debited with $"+amount;
                this.miniStatement.add(str);
                return str;

            }else
                return "Amount entered is high, please enter less amount !!! ";
        }else
            return "Account is already closed";

    }

    public double getBalance() {

        if(checkAccountStatus())
            return this.accountBalance;

        // why should the balance of an disabled account be -1??
        return -1.00;
    }

    // replace "changePIN" by "setPIN". The terms getter/setter are commonly in OOP. They make your code more readable to other programmers
    public boolean changePIN(String newPin) {
        if(checkAccountStatus()) {
            this.accountPIN = newPin;
            return true;
        }
        return false;
    }

    // replace "checkAccountStatus" by "getAccountStatus"
    private boolean checkAccountStatus() {
        return this.accountStatus;
    }

    public String closeAccount() {

        if(checkAccountStatus()) {
            System.out.printf("%s","Please collect $"+ getBalance());

            this.accountStatus = false;

            return ". Account is now closed";
        }
        return "Account is already closed";

    }

    public void printMiniStatement() {

        if(checkAccountStatus()) {
            Iterator itr = this.miniStatement.iterator();

            System.out.printf("%20s%n", "MINI STATEMENT");

            while(itr.hasNext()) {

                System.out.printf("%s%n", itr.next());

            }
        }

    }

}

User类

package templates;

public class User {

    private String firstName;
    private String lastName;
    private String address;
    private String phoneNumber;

    /*
    Here, the "this"-keyword was necessary. Otherwise method parameters will shadow the field you want to assign a value to.
     */
    public User(String firstName,String lastName,String address,String phoneNumber) {

        this.firstName = firstName;
        this.lastName = lastName;
        this.address = address;
        this.phoneNumber = phoneNumber;

    }

    /* why abbreviate "firstName" to "fname"? Simply use "firstName" as your method parameter.
       This way you can avoid unnecessary confusion for other programmers. Keep the "this"-keyword to avoid ambiguity
    */
    public boolean setFirstName(String fname) {

        if(!fname.isEmpty()) {
            this.firstName = fname;

            return true;
        }

        return false;

    }

    public String getFirstName() {
        return this.firstName;
    }

    public boolean setLastName(String lname) {

        if(!lname.isEmpty()) {
            this.lastName = lname;

            return true;
        }

        return false;

    }

    public String getLastName() {
        return this.lastName;
    }


    public boolean setAddress(String addr) {

        if(!addr.isEmpty()) {
            this.address = addr;

            return true;
        }

        return false;

    }

    public String getAddress() {
        return this.address;
    }

    public boolean setPhoneNumer(String phonenum) {

        if(phonenum.length() == 10) {
            this.phoneNumber = phonenum;

            return true;
        }

        return false;

    }

    public String getPhoneNumber() {
        return this.phoneNumber;
    }
}

ATMTest类

package test;

import java.util.Iterator;

// avoid wildcard imports
import templates.*;

public class ATMTest {

    public static void main(String[] args) {

        Account savings = new Account();

        User user1 = new User("Dummy","Name","27, First Floor, Suok-I","8888888888");

        System.out.printf("%s%n", "Account Balance is $"+savings.getBalance());

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

        System.out.printf("%s%n", savings.doWithdraw(50));

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

        System.out.printf("%s%n", savings.doWithdraw(5540));

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

        System.out.printf("%s%n", savings.doWithdraw(3350));

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

        System.out.printf("%s%n", savings.doWithdraw(1090));

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

        System.out.printf("%s%n", savings.doWithdraw(90));

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

        System.out.printf("%s%n", savings.doWithdraw(966));

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

        System.out.printf("%s%n", "Account Balance is $"+savings.getBalance());

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

        savings.changePIN("1611");

        /*
        // the following line can't be compiled -> incompatible types
        Iterator itr = savings.printMiniStatement();

        System.out.printf("%20s%n", "MINI STATEMENT");

        while(itr.hasNext()) {

            System.out.printf("%s%n", itr.next());

        }
        */

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

        // use the "toString"-Method here to print "user1"
        System.out.printf("%s%n", user1.getFirstName());

        System.out.printf("%s%n", user1.getLastName());

        System.out.printf("%s%n", user1.getAddress());

        System.out.printf("%s%n", user1.getPhoneNumber());

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

        user1.setFirstName("Rain");

        user1.setLastName("Man");

        user1.setAddress("32, Second Floor, Suok-I");

        user1.setPhoneNumer("9999999999");

        System.out.printf("%s%n", user1.getFirstName());

        System.out.printf("%s%n", user1.getLastName());

        System.out.printf("%s%n", user1.getAddress());

        System.out.printf("%s%n", user1.getPhoneNumber());

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

        System.out.printf("%s%n", savings.closeAccount());

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

        System.out.printf("%s%n", savings.doWithdraw(1111));

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

    }

}
```#qcStackCode#

票数 1

页面原文内容由Code Review提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://codereview.stackexchange.com/questions/260493

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