java - 文本文件中有多少个唯一单词以及这些唯一单词的计数是多少

Question

import java.io.FileReader;
import java.util.Arrays;


public class dictionary {

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

        // Read all the words from the dictionary (text.txt) into an array
        BufferedReader br = new BufferedReader(new FileReader("text.txt"));
        int bufferLength = 1000000;
        char[] buffer = new char[bufferLength];
        int charsRead = br.read(buffer, 0, bufferLength);
        br.close();
        String text = new String(buffer);
        text = text.trim();
        text = text.toLowerCase();
        String[] words = text.split("\n");

        System.out.println("Total number of words in text: " + words.length);

        //to find for unique text
        String[] uniqueText = {};
        int[] textCount = new int[uniqueText.length];

        for (int i = 0; i < words.length; i++) {

            if (uniqueText[i].contains(words[i])) {
                textCount[i]++;

            } else {
                uniqueText[i] = words[i];

            }

        }
    }

嗨，我无法在这里弄清楚我的代码，而且我真的不知道如何用语言表达我的问题，所以我将使用伪代码。

线程“main”java.lang.NullPointerException 中出现异常

if (uniqueText[i].contains(words[i]))

create a string array [uniqueText]
create an int array [uniqueTextCount]

   For every word in text

      if word[i] exists in uniqueText(
            +uniqueTextCount[i])
      else(
           + the new unique word to uniqueText)

Answer 1

这里的问题是您正在初始化一个空白数组，String[] uniqueText = {};，然后尝试添加到该数组(uniqueText[i] = Words[我];)。我相信您正在寻找类似 List 的东西，其中大小可以是动态的，因为我们从一开始就不知道有多少个独特的单词。或者我们甚至可以更进一步，使用一个 Map，它也具有动态大小，但使用键和值，非常适合这种情况，因为我们希望将单词链接到计数。

System.out.println("Total number of words in text: " + words.length);

Map<String, Integer> uniqueWordsAndCount = new HashMap<>();
for (String word : words) { 
    if (uniqueWordsAndCount.containsKey(word)){ //If word is in our map already, increase count
        uniqueWordsAndCount.put(word, uniqueWordsAndCount.get(word)+1);
    }else{  //If not in our map, add it and set count to 1
        uniqueWordsAndCount.put(word, 1);
    }
} 
//Accessing the count of a word
uniqueWordsAndCount.get("someWord"); //This returns the count