试图访问Java CSV列的问题

Question

我有问题，我正在尝试从JAVA中的CSV归档访问列。我编写了一个函数，该函数从csv存档返回所有数据。但是我想根据条件返回1列。条件是列区域。

如果区域号为1，则结果例如是在SQL中。

选择区域，根据人口普查区域中“房屋”的总和（nviv）= 1

该区域返回1值，即所有列nviv的总和。我尝试这样做，但是在JAVA和OpenCSV中。

这是我的代码，我是Java编程的CSV档案库的新手。

package hogares;

import java.util.*;
import com.opencsv.*;
import java.io.*;

public class Hogares {

    public static final String SEPARADOR = ";";

    public static void main(String[] args){

        int opc;
        Scanner sc = new Scanner(System.in);

        System.out.println("MENU HOMES");
        System.out.println("");

        System.out.println("1. Count Regions by region number");
        System.out.println("2. Average of homes of blocks by region number");
        System.out.println("3. Blocks number by region number");
        System.out.println("4. Exit");
        System.out.println("");

        System.out.println("Select an option: ");
        opc = sc.nextInt();

        switch(opc){
            case 1:
                CountHome();
                break;
            case 2:
                AverageHome();
                break;
            case 3:
                BlocksNumber();
                break;
            case 4:
                System.out.println("EXITING...");
                System.out.println("");
                break;
            default:
                System.out.println("Invalid option...");
                break;
        }
    }

    private static void CountHome(){

        int region;
        Scanner lee = new Scanner(System.in);

        BufferedReader csvr = null;
        try {


            csvr = new BufferedReader(new FileReader("C:\\Users\\ADMIN\\Desktop\\census2010.csv"));

            String[] headers = new String[]{"REGION","PROVINCE","COMMUNE","DC","AREA","ZC_LOC","ID_ZONE_LOC","NVIV","NHOME","TIPE_HOME","TIPE_OPERATIVE"};

            System.out.println("Tell me a number: ");
            region = lee.nextInt();


            String line = csvr.readLine();
            while (null!=line) {
                headers = line.split(SEPARADOR);
                System.out.println(Arrays.toString(headers));


                System.out.println(Arrays.toString(headers));

                line = csvr.readLine();
            }
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        finally{

            if (csvr != null) {
                try {
                    csvr.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }

    private static void AverageHome() {

    }

    private static void BlocksNumber() {

    }
}

这是输出。记住，我试图根据此行的数字返回1个结果：

System.out.println("Tell me a number: ");
region = lee.nextInt();

Answer 1

添加了代码注释以进行解释

    private static void CountHome() {

        int requestedRegion;
        Scanner scanner = new Scanner(System.in);

        System.out.println("Tell me a number: ");
        requestedRegion = scanner.nextInt();

        try {
            FileReader filereader = new FileReader("C:\\\\Users\\\\ADMIN\\\\Desktop\\\\census2010.csv");

            // Use OpenCsv to read CSV file
            CSVReader csvReader = new CSVReader(filereader);

            System.out.println("REGION\tHOUSES");

            //Assign it to skip header row from records
            String[] nextLine = csvReader.readNext();

            //Take variable to for sum of nviv
            int houses = 0;

            // Read CSV record one by one
            while ((nextLine = csvReader.readNext()) != null) {

                // Get first column value which is region
                String region = nextLine[0];

                // Get nviv column value
                String nviv = nextLine[7];

                // Check region and nviv is not null and empty
                if (region != null && !region.isEmpty() && nviv != null && !region.isEmpty()) {

                    // Parse region string to integer
                    int currentRegion = Integer.parseInt(region);

                    // Check row region is equals to region entered by user
                    if (currentRegion == requestedRegion) {

                        // Parse nviv sting to integer
                        int currentNviv = Integer.parseInt(nviv);

                        // Sum nviv And get total houses
                        houses = houses + currentNviv;

                        // System.out.println(region + "\t" + nviv);
                    }
                } else {
                    System.out.println("Invalid data to proceed");
                }
            }
            System.out.println(requestedRegion + "\t" + houses);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

示例CSV数据：

REGION,PROVINCE,COMMUNE,DC,AREA,ZC_LOC,ID_ZONE_LOC,NVIV,NHOME,TIPE_HOME,TIPE_OPERATIVE
1,2,33,4,5,66,7,8,9,10,11
2,2,33,4,5,66,7,8,9,10,11
1,2,33,4,5,66,7,8,9,10,11
2,2,33,4,5,66,7,8,9,10,11
1,2,33,4,5,66,7,8,9,10,11
1,2,33,4,5,66,7,8,9,10,11
7,2,33,4,5,66,7,8,9,10,11
7,2,33,4,5,66,7,8,9,10,11
7,2,33,4,5,66,7,8,9,10,11
7,2,33,4,5,66,7,8,9,10,11
7,2,33,4,5,66,7,8,9,10,11
8,2,33,4,5,66,7,8,9,10,11
8,2,33,4,5,66,7,8,9,10,11
8,2,33,4,5,66,7,8,9,10,11
8,2,33,4,5,66,7,8,9,10,11
8,2,33,4,5,66,7,8,9,10,11

输出：

MENU HOMES

1. Count Regions by region number
2. Average of homes of blocks by region number
3. Blocks number by region number
4. Exit

Select an option: 
1
Tell me a number: 
7
REGION  HOUSES
7   40

如果CSV的行为空，会导致错误，

检查是否存在任何空行，如果找到则跳过

           // Read CSV record one by one
            while ((nextLine = csvReader.readNext()) != null) {

                // Check row empty, if found skip iteration
                if (nextLine.length != 0 && nextLine[0].trim().isEmpty()) {
                    continue;
                }