如何使用Java对文本文件中的记录进行排序？ [英] How do I sort records in a text file using Java?

问题描述

txt文件中数据的一些修改。
我已经尝试了建议的代码，但是我没有成功地使用这种格式在txt文件中写入它。我尝试了collection.sort，但是以长行写入数据。

Some amendment of the data in txt file. I have tried the suggested code but Im not successfully write it again in the txt file with this format.I've tried the collection.sort but it write the data in long line.

我的txt文件包含以下数据：

My txt file contain these data:

Monday
Jessica  Run      20mins
Alba     Walk     20mins
Amy      Jogging  40mins
Bobby    Run      10mins
Tuesday
Mess     Run      20mins
Alba     Walk     20mins
Christy  Jogging  40mins
Bobby    Run      10mins

如何按升序对这些数据进行排序，并在排序后再次存储在txt文件中？ p>

How can I sort those data in ascending order and store it again in txt file after sorting?

Monday
Alba     Walk     20mins
Amy      Jogging  40mins
Bobby    Run      10mins
Jessica  Run      20mins
Tuesday
Alba     Walk     20mins
Bobby    Run      10 mins
Christy  Jogging  40mins
Mess     Run      20mins
Jessica  Run      20mins

解决方案

这是我想出的东西：

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

public class Sort {

    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new FileReader("fileToRead"));
        Map<String, String> map=new TreeMap<String, String>();
        String line="";
        while((line=reader.readLine())!=null){
            map.put(getField(line),line);
        }
        reader.close();
        FileWriter writer = new FileWriter("fileToWrite");
        for(String val : map.values()){
            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
    }
}

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