How to implement Lingqiantong in Java

As shown in the picture:

Thoughts:

(1) You can record and consume income and save it in an array (but the array you have learned so far is of fixed length)

(2) You can use objects

(3) You can use String splicing

Complete the revenue entry, complete the function driver programmer to add new changes to the code

(1) To receive the amount of revenue entry, and update the balance

(2) Splice the characters String

(3) Find how to output the time, and modify its output format

The string splicing I used

Some instructions

Create a package com.project.money.oop

Then create two classes SmallChangeSys and SmallChangeSysOOP

SmallChangeSys is used to write the main method code as follows

package com.project.money.oop;

public class SmallChangeSys {
    public static void main(String[] args) {
        SmallChangeSysOOP p=new SmallChangeSysOOP();
        p.menu();
    }
}

SmallChangeSysOOP is used to implement specific functions

The code is as follows:

package com.project.money.oop;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
public class SmallChangeSysOOP {
    private  double in_money=0;//当前流动的钱
    private double balance=0;//余额
    private String detailed="------------零钱通明细--------------";
    private Date date = null;
    //可以用于日期格式化的
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
public void menu(){};
//1 零钱通明细
 public void detailed_(){};
 //2 收益入账"
 public void input(){};
 //3消费
    public void output(){};

}

Specify the role of each method:

public void menu() method

public void menu(){//菜单
        boolean loop=true;
        Scanner scanner = new Scanner(System.in);
        while(loop){//循环展示菜单
            System.out.println("\n============oop零钱通菜单==============");
            System.out.println("\t\t1 零钱通明细");
            System.out.println("\t\t2 收益入账");
            System.out.println("\t\t3 消费");
            System.out.println("\t\t4 退" + "\t" + "出");
            System.out.print("请选择1-4:");int key= scanner.nextInt();//选择；
            switch (key){
                case 1:detailed_();break;
                case 2:input();break;
                case 3:output();break;
                case 4:System.out.println("\t\t程序已经退出");loop=false;break;
            }

        }
    }

void detailed_ () method

public void detailed_(){
        System.out.println(detailed);//直接输出字符
    }

public void input() method

public void input(){//收益入账
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入金额：");
        this.in_money=scanner.nextDouble();

        while(in_money<0){
            System.out.println("======输入有误======");
            System.out.println("是否重新输入？Y（是）或 N（否） ");//可能点错了不是输入
            String in=scanner.next();//是否重新输入
            if(in.equals("n")||in.equals("N")){
                System.out.println("返回主页面中....");
                /*****************************************/
                try {
                    Thread.sleep( 1000 );//暂停1秒提升用户感受
                } catch (Exception e){}
                /*******************************************/
                return;//退出输入
            }

                System.out.println("请输入金额：");
                this.in_money=scanner.nextDouble();
        }
        this.balance+=this.in_money;
        String beizhu="";
        date = new Date();
        System.out.println("请输入备注：");
        beizhu=scanner.next();
        this.detailed+="\n收益入帐\t+" + this.in_money + "\t" + sdf.format(date) +
                "\t余额：" + this.balance+ "  备注：" +beizhu;
    }

public void output() method

 public void output(){
        System.out.println("请输入金额：");
        Scanner scanner = new Scanner(System.in);
        in_money=scanner.nextDouble();
        if(balance<in_money){
            System.out.println("余额不足，请充值");
            return;
        }
        while(in_money<0){
            System.out.println("输入错误，请重输");
            in_money=scanner.nextDouble();
            if(balance<in_money){
                System.out.println("余额不足，请充值");
                return;
            }
        }
        this.balance-=in_money;
        System.out.println("请输入备注：");
        String beizhu=scanner.next();
        this.detailed+="\n余额支出\t-" + this.in_money + "\t" + sdf.format(date) +
                "\t余额：" + this.balance+ "  备注：" +beizhu;

    }

SmallChangeSysOOP complete code

package com.project.money.oop;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
public class SmallChangeSysOOP {
    private  double in_money=0;//当前流动的钱
    private double balance=0;//余额
    private String detailed="------------零钱通明细--------------";
    private Date date = null;
    //可以用于日期格式化的
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");

    public void menu(){//菜单
        boolean loop=true;
        Scanner scanner = new Scanner(System.in);
        while(loop){//循环展示菜单
            System.out.println("\n============oop零钱通菜单==============");
            System.out.println("\t\t1 零钱通明细");
            System.out.println("\t\t2 收益入账");
            System.out.println("\t\t3 消费");
            System.out.println("\t\t4 退" + "\t" + "出");
            System.out.print("请选择1-4:");int key= scanner.nextInt();//选择；
            switch (key){
                case 1:detailed_();break;
                case 2:input();break;
                case 3:output();break;
                case 4:System.out.println("\t\t程序已经退出");loop=false;break;
            }

        }
    }
    //1 零钱通明细
    public void detailed_(){
        System.out.println(detailed);
    }
    //2 收益入账"
    public void input(){//收益入账
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入金额：");
        this.in_money=scanner.nextDouble();

        while(in_money<0){
            System.out.println("======输入有误======");
            System.out.println("是否重新输入？Y（是）或 N（否） ");//可能点错了不是输入
            String in=scanner.next();//是否重新输入
            if(in.equals("n")||in.equals("N")){
                System.out.println("返回主页面中....");
                /*****************************************/
                try {
                    Thread.sleep( 1000 );//暂停1秒提升用户感受
                } catch (Exception e){}
                /*******************************************/
                return;//退出输入
            }

                System.out.println("请输入金额：");
                this.in_money=scanner.nextDouble();
        }
        this.balance+=this.in_money;
        String beizhu="";
        date = new Date();
        System.out.println("请输入备注：");
        beizhu=scanner.next();
        this.detailed+="\n收益入帐\t+" + this.in_money + "\t" + sdf.format(date) +
                "\t余额：" + this.balance+ "  备注：" +beizhu;
    }
    //3消费
    public void output(){
        System.out.println("请输入金额：");
        Scanner scanner = new Scanner(System.in);
        in_money=scanner.nextDouble();
        if(balance<in_money){
            System.out.println("余额不足，请充值");
            return;
        }
        while(in_money<0){
            System.out.println("输入错误，请重输");
            in_money=scanner.nextDouble();
            if(balance<in_money){
                System.out.println("余额不足，请充值");
                return;
            }
        }
        this.balance-=in_money;
        System.out.println("请输入备注：");
        String beizhu=scanner.next();
        this.detailed+="\n余额支出\t-" + this.in_money + "\t" + sdf.format(date) +
                "\t余额：" + this.balance+ "  备注：" +beizhu;

    }


}

Some pictures

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