java - 读取和操作 CSV 文件

Question

我想读取 CSV 文件，如下所示:

DATE=2014-03-08;ID=01;AVG=10

public void readInputStream(InputStream in) throws IOException {
    BufferedReader br = null;
    String line = "";
    String cvsSplitBy = ";";

    try {


        br = new BufferedReader(new InputStreamReader(in, "UTF-8"));
        while ((line = br.readLine()) != null) {
            String[] date= line.split(cvsSplitBy);
            if (line.contains("DATE")){
            System.out.println(date[0]);
        }}
        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

我想按日期和 ID 求平均值？任何帮助

Answer 1

import java.io.*;
import java.util.*;

public class CsvSum{

static Map<String, Integer> map = new HashMap<String, Integer>();

public static void main(String args[]) throws Exception{
    File file = new File("test.csv");
    Scanner scanner = new Scanner(file);
    while(scanner.hasNext()){
        String line = scanner.next();
        String[] columns = line.split(";");

        String date = columns[0].replace("DATE=","");
        String id = columns[1].replace("ID=","");
        int avg = Integer.parseInt(columns[2].replace("AVG=",""));

        String key = date + "_" +id;
        if(!map.containsKey(key)){
            map.put(key,avg);
        }else{
            Integer existing = map.get(key);
            map.put(key, existing + avg);
        }
    }

    System.out.println(map);
}
}