Java模仿微信如何实现零钱通简易功能

本篇文章为大家展示了Java模仿微信如何实现零钱通简易功能，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。

1. 需求描述

使用Java 开发零钱通项目, 模仿微信实现简易功能，可以完成收益入账，消费，查看明细，退出系统等功能，先按照一般方法写，后期在改进为OOP

预期界面：（实际可能不同）

2. 需求分析

面对这样一个需求，先化繁为简

1. 写一个菜单

2. 完成零钱通明细.

3. 完成收益入账

4. 消费

5. 退出

6. 用户输入4退出时，给出提示"你确定要退出吗? y/n"，必须输入正确的y/n ，否则循环输入指令，直到输入y 或者 n

7. 在收益入账和消费时，判断金额是否合理，并给出相应的提示

3. 实现零钱通主要功能

3.1 写一个菜单

先完成显示菜单，并可以选择菜单，并且给出对应提示

public static void main(String[] args) {        // define related variables        Scanner scanner = new Scanner(System.in);        String key = "";        boolean loop = true;        do {            System.out.println("==========Small Change Menu==========");            System.out.println("\t\t\t1 show change details");            System.out.println("\t\t\t2 income entry");            System.out.println("\t\t\t3 consumption");            System.out.println("\t\t\t4 exit");            System.out.println("please choose 1-4:");            key = scanner.next();            //use switch to control            switch (key) {                case "1":                    System.out.println("1  show change details");                    break;                case "2":                    System.out.println("2 income entry");                    break;                case "3":                    System.out.println("3 consumption");                    break;                case "4":                    System.out.println("4 exit");                    System.out.println(" you have exit the SmallChange");                    loop = false;                    break;                default:                    System.out.println("err please choose again");            }        } while (loop);    }

3.2 零钱通明细

思路

(1) 可以把收益入账和消费保存到数组

(2) 可以使用对象

(3) 简单的话可以使用String拼接

这里直接采取第三种方式

改变一下switch的case1

 String details = "-----------------零钱通明细------------------";

   case "1":                    System.out.println(details);                    break;

3.3 收益入账

完成收益入账

定义新的变量

 double money = 0;        double balance = 0;        Date date = null; // date 是 java.util.Date 类型，表示日期        //if you don't like the default format of displaying date ,change it with sdf        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");

修改switch中的case2

 System.out.print("Income recorded amount:");                    money = scanner.nextDouble();                    //the range of money should be limited                    //give the hits of the illegal money value 就直接break                    balance += money;                    //拼接收益入账信息到 details                    date = new Date(); //Get the current time                    details += "\n收益入账\t+" + money + "\t" + sdf.format(date)+ "\t" + balance;                    break;

效果演示：

保证入账>0

3.4 消费

定义新的变量

 String note = "";

修改switch中的case3

  case "3":                    System.out.print("Consumption amount:");                    money = scanner.nextDouble();                    //the range of money should be limited                    System.out.print("Consumption Description:");                    note = scanner.next();                    balance -= money;                    //Splicing consumption information to details                    date = new Date();//Get the current time                    details += "\n"+note + "\t-" + money + "\t" + sdf.format(date) + "\t" + balance;                    break;

效果演示:

3.5 用户退出改进

给出确认,是否要退出

用户输入4退出时，给出提示"你确定要退出吗? y/n"，必须输入正确的y/n ，

否则循环输入指令，直到输入y 或者 n

(1) 定义一个变量 choice, 接收用户的输入

(2) 使用 while + break, 来处理接收到的输入时 y 或者 n

(3) 退出while后，再判断choice是y还是n ,就可以决定是否退出

(4) 建议一段代码完成功能，不混在一起

  case "4":                    String choice = "";                    while (true) {                        //The user is required to enter Y / N, otherwise it will cycle all the time                        System.out.println("你确定要退出吗? y/n");                        choice = scanner.next();                        if ("y".equals(choice) || "n".equals(choice)) {                            break;                        }                        //scheme 2//                        if("y".equals(choice)) {//                            loop = false;//                            break;//                        } else if ("n".equals(choice)) {//                            break;//                        }                    }                    if (choice.equals("y")) {                        loop = false;                    }                    break;

效果演示:

3.6 改进金额判断

收入时

 if (money <= 0) {                        System.out.println("The income entry amount must be greater than 0");                        break;                    }

支出时

   if (money <= 0 || money > balance) {                        System.out.println("Your consumption amount should be 0-" + balance);                        break;                    }

效果演示

4. 面向过程版实现

import java.text.SimpleDateFormat;import java.util.Date;import java.util.Scanner;public class SmallChangeSys {    // try to reduce complexity to simplicity//1.  First complete the display menu,// and you can select the menu to give the corresponding prompt//2.  Complete change details//3.  Complete income entry//4.  consumption//5.  exit//6.  When the user enters 4 to exit, the prompt "are you sure you want to exit?// Y / N" will be given. You must enter the correct Y / N,// otherwise cycle the input instruction until y or n is entered//7. When the income is recorded and consumed,// judge whether the amount is reasonable and give corresponding tips    public static void main(String[] args) {        // define related variables        Scanner scanner = new Scanner(System.in);        String key = "";        boolean loop = true;        //2. complete the change details        //(1) 可以把收益入账和消费，保存到数组 (2) 可以使用对象 (3) 简单的话可以使用String拼接        String details = "-----------------Change details------------------";        //3. complete income entry        double money = 0;        double balance = 0;        Date date = null; // date 是 java.util.Date 类型，表示日期        //if you don't like the default format of displaying date ,change it with sdf        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");        //4. consumption        //define new variable，store the reason why consume        String note = "";        do {            System.out.println("\n==========Small Change Menu==========");            System.out.println("\t\t\t1 show change details");            System.out.println("\t\t\t2 income entry");            System.out.println("\t\t\t3 consumption");            System.out.println("\t\t\t4 exit");            System.out.println("please choose 1-4:");            key = scanner.next();            //use switch to control            switch (key) {                case "1":                    System.out.println(details);                    break;                case "2":                    System.out.print("Income recorded amount:");                    money = scanner.nextDouble();                    //the range of money should be limited                    //commonly use  to judge the wrong situation make the code easy to read                    //give the hits of the illegal money value 就直接break                    if (money <= 0) {                        System.out.println("The income entry amount must be greater than 0");                        break;                    }                    balance += money;                    //Splicing consumption information to details                    date = new Date(); //Get the current time                    details += "\n" + "Income " + "\t" + "+" + money + "\t" + sdf.format(date) + "\t" + balance;                    break;                case "3":                    System.out.print("Consumption amount:");                    money = scanner.nextDouble();                    //the range of money should be limited                    if (money <= 0 || money > balance) {                        System.out.println("Your consumption amount should be 0-" + balance);                        break;                    }                    System.out.print("Consumption Description:");                    note = scanner.next();                    balance -= money;                    //Splicing consumption information to details                    date = new Date();//Get the current time                    details += "\n" + note + "\t-" + money + "\t" + sdf.format(date) + "\t" + balance;                    break;                case "4":                    String choice = "";                    while (true) {                        //The user is required to enter Y / N, otherwise it will cycle all the time                        System.out.println("你确定要退出吗? y/n");                        choice = scanner.next();                        if ("y".equals(choice) || "n".equals(choice)) {                            break;                        }                        //scheme 2//                        if("y".equals(choice)) {//                            loop = false;//                            break;//                        } else if ("n".equals(choice)) {//                            break;//                        }                    }                    if (choice.equals("y")) {                        loop = false;                    }                    break;                default:                    System.out.println("err please choose again");            }        } while (loop);        System.out.println(" you have exit the SmallChange");    }}

5. 优化成OOP版

很多东西可以直接复制过来变成方法,把原来的改过来是简单的

5.1 实现OOP版

那么先有一个执行的主类SmallChangeSysApp

//Call the object directly and display the main menupublic class SmallChangeSysApp {    public static void main(String[] args) {        new SmallChangeSysOOP().mainMenu();    }}

还有一个类专门是对象,我们叫它为SmallChangeSysOOP

import java.text.SimpleDateFormat;import java.util.Date;import java.util.Scanner;/** * This class is used to complete various functions of zero money pass * Using OOP (object-oriented programming) * Each function corresponds to a method */public class SmallChangeSysOOP {    //basic variables    boolean loop = true;    Scanner scanner = new Scanner(System.in);    String key = "";    //display details    String details = "-----------------Change details------------------";    //income    double money = 0;    double balance = 0;    Date date = null;    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");    // consume    String note = "";    public void mainMenu() {        do {            System.out.println("\n================Small Change Menu(OOP)===============");            System.out.println("\t\t\t1 show change details");            System.out.println("\t\t\t2 income entry");            System.out.println("\t\t\t3 consumption");            System.out.println("\t\t\t4 exit");            System.out.println("please choose 1-4:");            key = scanner.next();            switch (key) {                case "1":                    this.detail();                    break;                case "2":                    this.income();                    break;                case "3":                    this.pay();                    break;                case "4":                    this.exit();                    break;                default:                    System.out.println("Choose the wrong number please choose again");            }        } while (loop);    }    public void detail() {        System.out.println(details);    }    public void income() {        System.out.print("Income recorded amount:");        money = scanner.nextDouble();        if (money <= 0) {            System.out.println("The income entry amount must be greater than 0");            return; //exit and do not execute next sentence.change break to return        }        balance += money;        date = new Date();        details += "\nIncome \t+" + money + "\t" + sdf.format(date) + "\t" + balance;    }    public void pay() {        System.out.print("Consumption amount:");        money = scanner.nextDouble();        if (money <= 0 || money > balance) {            System.out.println("Your consumption amount should be 0-" + balance);            return;        }        System.out.print("consumption description:");        note = scanner.next();        balance -= money;        date = new Date();        details += "\n" + note + "\t-" + money + "\t" + sdf.format(date) + "\t" + balance;    }    //退出    public void exit() {        //When the user enters 4 to exit, the prompt "are you sure you want to exit?        // Y / N" will be given. You must enter the correct Y / n        String choice = "";        while (true) {            System.out.println("are you really gonna exit? y/n");            choice = scanner.next();            if ("y".equals(choice) || "n".equals(choice)) {                break;            }            //scheme 2//                        if("y".equals(choice)) {//                            loop = false;//                            break;//                        } else if ("n".equals(choice)) {//                            break;//                        }        }        if (choice.equals("y")) {            loop = false;        }    }}

5.2 OOP的好处

OOP版主函数很简单,只要new这个对象就可以了,关于这个对象的其他方法也好属性也好,不用放在主函数里面,那样在主函数也可以自由加上想加得到内容,未来假如有他人要用,不用把整个文件拷过去,只要把类交给对方即可,这样扩展和可读性大大提升,要加什么功能就再写方法原先的扩展功能很麻烦,要来回切

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