Java - 文本到数组到文本

Question

我正在寻找从一个小文本文件中读取整数+字符串的最佳方法，将它们保存在一个数组中，添加一些新的整数+字符串，按整数对它们进行排序，然后在同一个文件中写入最高的几个。 （比如高分）

示例：

sth.txt：

5 aa
4 bb
3 cc
3 dd

进入

a["5 aa","4 bb","3 cc","3 dd"] 

添加一些新字符串

a["5 aa","4 bb","3 cc","3 dd","1 aa","7 bb"]

排序后写回sth.txt

7 bb
5 aa
4 bb
3 cc

如何在 Java 中做到这一点？

Answer 1

您可以按如下操作，代码中包含一个 cmets 以便更好地理解。

public static void main(String[] args) throws IOException {
    Data[] map = new Data[6];
    //Then read the data from your file , in my case
    //i will make a dummy data.
    map[0] = new Data(5, "aa");
    map[1] = new Data(4, "bb");
    map[2] = new Data(3, "cc");
    map[3] = new Data(3, "dd");
    map[4] = new Data(1, "aa");
    map[5] = new Data(7, "bb");
    //Then sorting this array
    java.util.Arrays.sort(map);
    //Then print the highet 4 records
    for (int i = 0; i < 4; i++) {
        System.out.println(map[i].FirstPart + " " + map[i].SecondPart);
    }
}

假设记录的第一部分是int 类型，第二部分是String，则创建一个适合您需要的类

class Data implements Comparable<Data> {

    int FirstPart;
    String SecondPart;

    public Data(int FirstPart, String SecondPart) {
        this.FirstPart = FirstPart;
        this.SecondPart = SecondPart;
    }
//compareTo method will be called whenever you call a sort method like
// "java.util.Arrays.sort(map);" in the main method

    @Override
    public int compareTo(Data o) {
        if (this.FirstPart < o.FirstPart) {
            return 1;
        } else {
            return -1;
        }
    }
}

输出：

7 bb
5 aa
4 bb
3 dd

Answer 2

检查以下解决方案--

abc.txt
4 test1
6 test2
0 test3
12 test4
5 test5
9 test6

---

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;


public class ReadWriteDataInFile {

    public static void main(String[] args) throws IOException {
        String path="C:\\test\\";
        String fileName=path+"abc.txt";
        String newFileName=path+"abcNew.txt";

        System.out.println("Reading Data from File "+fileName + " started...");
        Map<Integer, String> readDataFromTextFile = readDataFromTextFile(fileName);

        System.out.println("Writing Sorted Data to File "+newFileName + " started...");
        writeDataInNewFile(readDataFromTextFile,newFileName);
        System.out.println("Writing Data to File Completed...");
    }


    private static void writeDataInNewFile(Map<Integer, String> readDataFromTextFile, String newFileName) throws IOException {

        PrintWriter writer = new PrintWriter(newFileName, "UTF-8");

        Iterator it = readDataFromTextFile.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry pair = (Map.Entry)it.next();
            String data1=pair.getKey() + " " + pair.getValue();
            writer.println(data1);
        }
        writer.close();
    }

    private static Map<Integer, String> readDataFromTextFile(String fileName) throws IOException {

        FileInputStream fis = new FileInputStream(fileName);
        InputStreamReader input = new InputStreamReader(fis);
        BufferedReader br = new BufferedReader(input);

        String data;
        String result[] ;

        Map<Integer,String> dataMap= new TreeMap<Integer,String> ();
        while ((data = br.readLine()) != null) {
            result = data.split(" ");
            dataMap.put(Integer.parseInt(result[0]), result[1]);
        }
        return dataMap;
    }
}

---

newabc.txt
0 test3
4 test1
5 test5
6 test2
9 test6
12 test4

---

Answer 3

这里是示例解决方案，包括读取和写入文件：

public class Main {
    static class Entry<T, U> {
        public T value1;
        public U value2;

        public Entry(T value1, U value2) {
            this.value1 = value1;
            this.value2 = value2;
        }
    }

    static Entry<Integer, String> parseLine(String line) {
        String[] intAndString = line.split(" ");
        Integer i = Integer.parseInt(intAndString[0]);
        String s = intAndString[1];
        return new Entry<>(i, s);
    }

    public static void main(String[] args) throws IOException {
        Path path = Paths.get("spl.txt");
        List<Entry<Integer, String>> resultList = new LinkedList<>();
        try (BufferedReader reader = Files.newBufferedReader(path)) {
            String nextLine;
            while ((nextLine = reader.readLine()) != null) {
                if (nextLine.equals("\n") || nextLine.isEmpty()) continue;
                resultList.add(parseLine(nextLine));
            }
        }
        Collections.sort(resultList, (e1, e2) -> e1.value1 - e2.value1 != 0 ? e1.value1 - e2.value1 : e1.value2.compareTo(e2.value2));
        try (BufferedWriter writer = Files.newBufferedWriter(path)) {
            resultList.forEach((e) -> {
                try {
                    writer.write(e.value1 + " " + e.value2 + "\n");
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            });
        }
    }
}

由于可读性而省略了类条目的封装。
按升序顺序排序。
希望它会有所帮助。