Question

我有一个.csv文件作为输入。我需要一个Java程序来为我读取这个文件，并根据csv中的日期字段生成一个排序输出。输出文件格式必须为.xml

我有以下代码，虽然我是JAVA的新手，请帮忙。

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

public class Sort {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new FileReader("data1.csv"));
        Map<String, List<String>> map = new TreeMap<String, List<String>>();
        String line = reader.readLine();//read header
        while ((line = reader.readLine()) != null) {
            String key = getField(line);
            List<String> l = map.get(key);
            if (l == null) {
                l = new LinkedList<String>();
                map.put(key, l);
            }
            l.add(line);

        }
        reader.close();
        FileWriter writer = new FileWriter("sorted_numbers.txt");
        writer.write("UserID, Module, Mark\n");
        for (List<String> list : map.values()) {
            for (String val : list) {
                writer.write(val);
                writer.write("\n");
            }
        }
        writer.close();
    }

    private static String getField(String line) {
        return line.split(",")[0];// extract value you want to sort on
    }
}

Answer 1

您可以在java中使用csvreader来有效地阅读csv文件，而不是BufferedReader

Read a csv file

Answer 2

   public class ReadCVS {

public static void main(String[] args) throws ParseException {

    ReadCVS obj = new ReadCVS();
    obj.run();

}

public void run() throws ParseException {

    String csvFile = "config/one.csv";
    BufferedReader br = null;
    String line = "";
    String cvsSplitBy = ",";

    try {

        Map<Date, String> maps = new HashMap<Date, String>();

        br = new BufferedReader(new FileReader(csvFile));
        while ((line = br.readLine()) != null) {

            String[] country = line.split(cvsSplitBy);
            SimpleDateFormat sdf = new SimpleDateFormat("dd:MM:yyyy");
            Date date = sdf.parse(country[2]);

                            //country[2] is date
            maps.put(date, line);

        }
        System.out.println("Unsort Map......");
        // printMap(maps);
        System.out.println("Sorted Map......");
        Map<Date, String> treeMap = new TreeMap<Date, String>(maps);
        printMap(treeMap);

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

    System.out.println("Done");
}

public static void printMap(Map<Date, String> map) {
    for (Map.Entry entry : map.entrySet()) {
        System.out.println("Key : " + entry.getKey() + " Value : " + entry.getValue());
    }
}

}

Java程序读取.csv并提供已排序的.xml输出

2 个答案: