Java哈希表：包含键can'；找不到现有密钥

想象我有一个dictionary.csv文件：

"apple", "n.", "a red fruit"
"exercise", "n.", "sport"
"exercise", "v.", "play sport"

我已将其读入类型哈希表：

但是，content.containsKey（“苹果”）返回false。我尝试了hashmap和concurrentHashMap，但效果并不理想

下面是我的字典类代码

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Hashtable;

public class Dictionary {

    private String filename;
    private Hashtable<String, ArrayList<ArrayList<String>>> content = new Hashtable<>();

    public Dictionary(String filename) throws FileNotFoundException {
        // set the file name
        this.filename = filename;
        // read dictionary file into content
        try (BufferedReader br = new BufferedReader((new FileReader(filename)))) {
            String line;
            // read every line
            while ((line = br.readLine()) != null){
                String[] values = line.split(",");
                assert(values.length == 3);

                // split word,
                String word = values[0].toLowerCase();
                ArrayList<String> meaning = new ArrayList<>();
                meaning.add(values[1]);
                meaning.add(values[2]);

                // add word and meaning to the content
                if (content.containsKey(word)){
                    ArrayList newMeanings = content.get(word);
                    newMeanings.add(meaning);
                    content.put(word, newMeanings);
                }
                else {
                    ArrayList<ArrayList<String>> meanings = new ArrayList<>();
                    meanings.add(meaning);
                    content.put(word, meanings);
                }

            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void getMeaning(String rawWord){
        String word = rawWord.toLowerCase();

        if (content.containsKey(word)){
            ArrayList<ArrayList<String>> meanings = content.get(word);
            int numMeanings = meanings.size();

            for (int i = 0; i < numMeanings; i++){
                String[] meaningLst = (String[]) meanings.get(i).toArray();
                System.out.println("Meaning " + (i+1) + ": " + meaningLst[0] + ". " + meaningLst[1]);
            }
        }
        else {
            System.out.println("Word not found");
        }
    }
}

---

我认为您是将

“apple”

作为键插入，而不是

apple

。删除双引号。 更改：

致：

---

您好，问题在于输入内容应该是内容。containsKey（“\”apple\”）不是

---

content.containsKey（“apple”）或请删除dictionary.csv文件中的“。

切勿在新代码中使用

Hashtable

。请改用

Map

和

HashMap

。（并将变量声明为

Map

等，而不是使用特定的集合类型。）我认为您正在插入

“apple”“

作为一个键，而不是

apple

。删除双引号。使用现有库读取CSV，不要自己解析它，因为它会导致类似这样的问题。我支持@MarkrotVeel，并想指出数据看起来不一致，例如在

“apple”

之后，您有一个

：

作为分隔符，而在

“exercise”

之后，您有一个

=

作为分隔符。但请注意，这将删除键中的所有引号，而不仅仅是第一个和最后一个引号

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Hashtable;

public class Dictionary {

    private String filename;
    private Hashtable<String, ArrayList<ArrayList<String>>> content = new Hashtable<>();

    public Dictionary(String filename) throws FileNotFoundException {
        // set the file name
        this.filename = filename;
        // read dictionary file into content
        try (BufferedReader br = new BufferedReader((new FileReader(filename)))) {
            String line;
            // read every line
            while ((line = br.readLine()) != null){
                String[] values = line.split(",");
                assert(values.length == 3);

                // split word,
                String word = values[0].toLowerCase();
                ArrayList<String> meaning = new ArrayList<>();
                meaning.add(values[1]);
                meaning.add(values[2]);

                // add word and meaning to the content
                if (content.containsKey(word)){
                    ArrayList newMeanings = content.get(word);
                    newMeanings.add(meaning);
                    content.put(word, newMeanings);
                }
                else {
                    ArrayList<ArrayList<String>> meanings = new ArrayList<>();
                    meanings.add(meaning);
                    content.put(word, meanings);
                }

            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void getMeaning(String rawWord){
        String word = rawWord.toLowerCase();

        if (content.containsKey(word)){
            ArrayList<ArrayList<String>> meanings = content.get(word);
            int numMeanings = meanings.size();

            for (int i = 0; i < numMeanings; i++){
                String[] meaningLst = (String[]) meanings.get(i).toArray();
                System.out.println("Meaning " + (i+1) + ": " + meaningLst[0] + ". " + meaningLst[1]);
            }
        }
        else {
            System.out.println("Word not found");
        }
    }
}

import java.io.FileNotFoundException;

public class Main {
    public static void main(String ars[]) throws FileNotFoundException {
        Dictionary dictionary = new Dictionary("dictionary.csv");
        dictionary.getMeaning("apple");
    }
}

String word = values[0].toLowerCase();

String word = values[0].toLowerCase();
word = word.substring(1, word.length()-1);