在昨天题目基础上做挑战问题：

在金额上增加一个$符号 和逗号。- 这个在展示函数上直接增加即可。以金额高低来做排序。重写程序，主要用csv 的解析库来实现解析效果。

挑战2两个求解思路，

方法1 ： 建设2个字典，以Salary 为 key， 以First 和 Last 为value。 这样做排序的时候，先对Salary list 做排序， 然后基于这两个字典做查询即可。

方法2: 把Salary 的 list 中的元素index 单独抽出来，在做排序的时候，记录原始index的最后位置，再根据这个位置在list 里寻找数据。--这个之前挑战已经做过了，有demo。

方法3: 把这些内容存到数据库里，做一条查询即可，再做展示。

挑战3的代码如下：

python 版本：

import csvclass Parsedatafile:    originallist = []    firstcolumn = []    seconcolumn = []    thirdcolumn = []    def readdatafile(this):        # 从指定的文件中读取数据，并读入到一个列表中        filename = input("Please provde the name of the file from which you want open")        with open(filename, "r") as f:            reader = csv.reader(f)            for line in reader:                this.originallist.append(line)            f.close()        print("this is the list we get from the file {0}".format(this.originallist))    def processlist(this):        # 对列表做格式化，并生成对应的三个队列        for i in this.originallist:            this.firstcolumn.append(i[0])            this.seconcolumn.append(i[1])            this.thirdcolumn.append(i[2])        print("This is the firstcolumn list: {0}".format(this.firstcolumn))        print("This is the secondcolumn list: {0}".format(this.seconcolumn))        print("This is the thirdcolumn list: {0}".format(this.thirdcolumn))    def displaylist(this):        # 对处理后的队列操作，逐行做展示        # 找到每个列表里面最宽的元素        col1length = 0        col2length = 0        col3length = 0        for i in this.firstcolumn:            if len(i) > col1length:                col1length = len(i)        for i in this.seconcolumn:            if len(i) > col2length:                col2length = len(i)        for i in this.thirdcolumn:            if len(i) > col3length:                col3length = len(i)        space = " "        line1 = "Last" + space * (col1length - 4 + 1) + "First" + space * (col2length - 5 + 1) + "Salary" + space * (                    col3length - 6 + 1)        line2 = len(line1) * "-"        print(line1)        print(line2)        for i in range(0, len(this.firstcolumn)):            print(this.firstcolumn[i].ljust(col1length + 1), end="")            print(this.seconcolumn[i].ljust(col2length + 1), end="")            print(this.thirdcolumn[i])lesson42 = Parsedatafile()lesson42.readdatafile()lesson42.processlist()lesson42.displaylist()

python csv 函数的详细用法可以参考网文，

这里主要是把每一行的数据解析成了一个队列。

看到下面运行效果是一样的。

Java 版本：

使用csvReader来解析CSV 文件，效果类似，也是解析成了一个队列，从队列里面直接读取元素即可。

import java.io.BufferedReader;import java.io.FileReader;import java.io.IOException;import java.io.InputStreamReader;import java.nio.Buffer;import java.util.ArrayList;import java.util.Scanner;import com.opencsv.CSVReader;public class ParseFilev2{    private ArrayList<String>  originallist = new ArrayList<>();    private ArrayList<String>  firstcolumn = new ArrayList<>();    private ArrayList<String>  secondcolumn = new ArrayList<>();    private ArrayList<String>  thirdcolumn = new ArrayList<>();    private Scanner sc = new Scanner(System.in);    void readdatafile(){        System.out.println("Please provde the name of the file from which you want open");        String filename = sc.nextLine();        try{            String[] nextLine;            CSVReader csvReader = new CSVReader(new FileReader(filename));            while((nextLine=csvReader.readNext())!= null)            {                firstcolumn.add(nextLine[0]);                secondcolumn.add(nextLine[1]);                thirdcolumn.add(nextLine[2]);                originallist.add(nextLine[0]+","+nextLine[1]+","+nextLine[2]);            }        }catch(IOException e){        }        System.out.println("This is the original list we get from the file"+ originallist.toString());    }    //从指定的文件中读取数据，并读入到一个列表中    void displaylist(){        //对处理后的队列操作，逐行做展示        //找到每个列表里面最宽的元素        int fcmlength = 0;        int scmlength = 0;        int tcmlength = 0;        for (int i = 0 ; i< firstcolumn.size();i++){            if (fcmlength< firstcolumn.get(i).length())            {fcmlength = firstcolumn.get(i).length();}            if (scmlength< secondcolumn.get(i).length())            {scmlength = secondcolumn.get(i).length();}            if (tcmlength< thirdcolumn.get(i).length())            {tcmlength = thirdcolumn.get(i).length();}        }        fcmlength = fcmlength + 1;        scmlength = scmlength + 1;        tcmlength = tcmlength + 1;        System.out.printf("%-"+fcmlength+"s","Last");        System.out.printf("%-"+scmlength+"s","First");        System.out.printf("%-"+tcmlength+"s\n","Salary");        for(int j=0;j< fcmlength+scmlength+tcmlength;j++)        {            System.out.printf("-");        }        System.out.println();        for( int k =0 ;k < firstcolumn.size();k++)        {            System.out.printf("%-"+fcmlength+"s", firstcolumn.get(k));            System.out.printf("%-"+scmlength+"s", secondcolumn.get(k));            System.out.printf("%-"+tcmlength+"s", thirdcolumn.get(k));            System.out.println();        }    }    public static void main(String[] args)    {        ParseFilev2 lesson42 = new ParseFilev2();        lesson42.readdatafile();        lesson42.displaylist();    }}

效果图：