如何使用Java对文本文件中的记录进行排序？

Question

对txt文件中的数据进行了一些修改.我已经尝试了建议的代码,但我没有成功地用这种格式在txt文件中再次写它.我尝试了collection.sort但是它用长线写了数据.

我的txt文件包含以下数据:

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,并在排序后将其再次存储在txt文件中？

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

Answer 1

这是我想出来的:

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
    }
}

Answer 2

这是一种非常懒惰的方法，因为您只对第一个单词进行排序：

    ArrayList<String> rows = new ArrayList<String>();
    BufferedReader reader = new BufferedReader(new FileReader("input.txt"));

    String s;
    while((s = reader.readLine())!=null)
        rows.add(s);

    Collections.sort(rows);

    FileWriter writer = new FileWriter("output.txt");
    for(String cur: rows)
        writer.write(cur+"\n");

    reader.close();
    writer.close();

Answer 3

package com.myFiles;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Collections;

public class FilesReaderWriter {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = null;
        PrintWriter outputStream = null;
        ArrayList<String> rows = new ArrayList<String>();

        try {
            reader  = new BufferedReader(new FileReader("Input.txt"));
            outputStream = new PrintWriter(new FileWriter("Output.txt"));

            String file;
            while ((file = reader .readLine()) != null) {
                rows.add(file);
            }
            Collections.sort(rows);
            String[] strArr= rows.toArray(new String[0]);
            for (String cur : strArr)
                outputStream.println(cur);
        } finally {
            if (reader  != null) {
                inputStream.close();
            }
            if (outputStream != null) {
                outputStream.close();
            }
        }
    }

}

Answer 4

使用sort：

aaron@ares ~$ sort data.txt 
Alba     Walk     20mins
Amy      Jogging  40mins
Bobby    Run      10mins
Jessica  Run      20mins

aaron@ares ~$ sort data.txt > sorted.txt
aaron@ares ~$ cat sorted.txt
Alba     Walk     20mins
Amy      Jogging  40mins
Bobby    Run      10mins
Jessica  Run      20mins

...或使用python：

aaron@ares ~$ python -c "import sys; print ''.join(sorted(sys.stdin))" < data.txt > sorted.txt
aaron@ares ~$ cat sorted.txt 
Alba     Walk     20mins
Amy      Jogging  40mins
Bobby    Run      10mins
Jessica  Run      20mins