将文本文件插入地图<Integer, Map<Integer, Double>>

Question

这是我的第一个问题，请多多包涵。我有一个看起来像这样的文本文件；

userId,itemId,rating
1,101,2.5
4,103,3.0
1,103,3.0
6,104,3.5
2,101,3.0
4,106,4.5
2,103,1.5
5,102,4.0
2,105,3.5
7,106,3.0
3,101,2.5
3,102,3.0

我想要完成的是每行读取文件行并分隔每个值。完成后将所有唯一的 userIds 放在这张地图的关键部分； Map<Integer, Map<Integer, Double>>。并将带有评级的itemIds放在与第一个地图的键对应的第二个地图中。你还能跟着我吗？？这是我到目前为止生成的代码，不是我想要的结果。

这是我的用户 class:

package com.example;

import java.util.HashMap;
import java.util.Map;

public class User {
    private int mUserId;
    private Map<Integer, Double> mRatedItems;

    public User(int userId) {
        mUserId = userId;
        mRatedItems = new HashMap<>();
    }

    public int getUserId() {
        return mUserId;
    }

    public void setUserId(int userId) {
        mUserId = userId;
    }

    public Map<Integer, Double> getRatedItems() {
        return mRatedItems;
    }

    public void addRatedItems(int itemId, double rating) {
        mRatedItems.put(itemId, rating);
    }
}

这是我需要修改的文件：

package com.example;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class TextFile {
    List<User> mUserIdList;
    private User mUser;

    public Map<Integer, Map<Integer, Double>> readFile(String fileName) {
        mUserIdList = new ArrayList<>();
        Map<Integer, Map<Integer, Double>> userItemData = new HashMap<>();

        try (
            FileInputStream fis = new FileInputStream(fileName);
            BufferedReader reader = new BufferedReader(new InputStreamReader(fis))
        ) {
            String line;
            while ((line = reader.readLine()) != null) {
                String[] args = line.split(",");

                int userId = Integer.parseInt(args[0]);
                int itemId = Integer.parseInt(args[1]);
                double rating = Double.parseDouble(args[2]);

                if (!mUserIdList.contains(userId)) {
                    mUser = new User(userId);
                    mUserIdList.add(mUser);
                }

                if (!mUserIdList.isEmpty()) {
                    addItemRatings(userId, itemId, rating);
                }

                if (!checkDuplicates()) {
                    userItemData.put(mUser.getUserId(), mUser.getRatedItems());
                }
            }
        } catch (IOException e) {
            System.out.printf("Problem loading: %s %n", fileName);
            e.printStackTrace();
        }

        return userItemData;
    }  

    private boolean checkDuplicates() {
        Set<Integer> set = new HashSet<>();
        for (User user : mUserIdList) {
            if (!set.add(user.getUserId())) {
                return true;
            }
        }
        return false;
    }

    public void addItemRatings(int userId, int itemId, double rating) {
        for (User user : mUserIdList) {
            if (user.getUserId() == userId) {
                user.addRatedItems(itemId, rating);
            }
        }
    }

    public int showTextLines(String fileName) {
        int textLines = 0;
        try (
                FileInputStream fis = new FileInputStream(fileName);
                BufferedReader reader = new BufferedReader(new InputStreamReader(fis))
        ) {
            while (reader.readLine() != null) {
                textLines++;
            }
            reader.close();
        } catch (IOException e) {
            System.out.printf("Problem showing total lines from: %s %n", fileName);
            e.printStackTrace();
        }
        return textLines;
    }
}

这是我的主class:

package com.example;

import java.util.Map;

public class Main {

    public static void main(String[] args) {
        TextFile textFile = new TextFile();
        String location = "D:\IdeaProjects\KMeans\src\com\quincy\userItem1.data";
        Map<Integer, Map<Integer, Double>> readFile = textFile.readFile(location);
        int textLines = textFile.showTextLines(location);
        System.out.printf("File: %s %n", readFile);
        System.out.printf("Number of lines in file: %s %n", textLines);
    }
}

我的输出是：

File: {1={101=2.5, 103=3.0}, 4={103=3.0, 106=4.5}} 
Number of lines in file: 12

我的代码只添加前两个 userId 及其相应的 itemId 和评级。有人可以向我解释我做错了什么吗？也许可以展示我如何改进此代码以使其正常工作？？

提前致谢。

Answer 1

问题出在您的 checkDuplicates() 方法中。我不知道你到底想在那个功能上实现什么，但如果你想检查重复。那么，我建议你像这样使用函数containsKey()。

if (!userItemData.containsKey(mUser.getUserId())) {
     userItemData.put(mUser.getUserId(), mUser.getRatedItems());
}

将文本文件插入地图<Integer, Map<Integer, Double>>

Inserting a text file into a Map<Integer, Map<Integer, Double>>

java

arraylist

object

hashmap