java - 如何从最高到最低排列列表中的项目(使用 I/O 出现单词)？

Question

我有一个有效的单词出现程序，花了我一段时间来编码(在 Java 中仍然是新的)，我想知道我是否可以获得一些帮助。这是我到目前为止的代码:

import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class TestWordOccurenceProgram {

public static void main(String[] args) {

    String thisLine = null;
    try {
        FileReader fr = new FileReader("myTextDocument.txt");
        BufferedReader br = new BufferedReader(fr);

        //List<String> wordList = new ArrayList<>();
        List<String> words = new ArrayList<>();
        // make ArrayList of integers
        List<Integer> counts = new ArrayList<>();

        String word = "";

        while ((thisLine = br.readLine()) != null ) {
            word = word.concat(thisLine);
            word = word.concat(" ");
        }

        String[] wordList = word.split("\\s");


        for (int i = 0; i < wordList.length; i++) {
            String temp = wordList[i];
            if(words.contains(temp)) {
                int x = words.indexOf(temp);
                int value = counts.get(x);
                value++;
                counts.set(x, value);
            }
            else {
                words.add(temp);
                counts.add(1);
            }
        }

        for (int i = 0; i < words.size(); i++) {
        System.out.println(words.get(i) + ": " + counts.get(i));

        }

        br.close();

    } catch (FileNotFoundException e) {
        e.printStackTrace();
        System.exit(1);

    } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }
}

以下是“myTextDocument.txt”的内容:

i am a rabbit
a happy rabbit am
yay i am a rabbit
a rabbit i am yay

这是我的输出:

i: 3
am: 4
a: 4
rabbit: 4
happy: 1
yay: 2

有谁知道我是否可以将这些项目从出现次数最多的单词排列到出现次数最少的单词？任何帮助都会很棒!

Answer 1

您可以使用映射而不是列表。并使用比较方法通过其值对 map 进行排序。引用这段代码:

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class PQ {

public static void main(String[] args) {

    String thisLine = null;
    try {
        FileReader fr = new FileReader("D:\\test.txt");
        BufferedReader br = new BufferedReader(fr);
        HashMap<String,Integer> map = new HashMap<String,Integer>();
        ValueComparator comparator =  new ValueComparator(map);
        TreeMap<String, Integer> treemap = new TreeMap<String, Integer>(comparator);

        while((thisLine = br.readLine()) != null){
            String[] str = thisLine.split("\\s+");
            for(String s:str){
                if(map.containsKey(s)){
                    Integer i = map.get(s);
                    i++;
                    map.put(s,i);
                }else{
                    map.put(s, 1);
                }
            }
        }
        treemap.putAll(map);
        System.out.println(treemap);
        br.close();

    } catch (FileNotFoundException e) {
        e.printStackTrace();
        System.exit(1);

    } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }
}

class ValueComparator implements Comparator<String>{

    Map<String, Integer> base;
    public ValueComparator(Map<String, Integer> base) {
        this.base = base;
    }

    public int compare(String a, String b) {
        if (base.get(a) >= base.get(b)) {
            return -1;
        } else {
            return 1;
        }
    }
}