如何使用Java实现课程评价分析功能

public class CourseEvaluation {
    private String courseId;
    private String studentId;
    private int rating; // 评分，例如1-5分
    private String comment;
    private long timestamp;

    // 构造方法、getter和setter省略
}
  

import java.util.ArrayList;
import java.util.List;

public class EvaluationManager {
    private List evaluations = new ArrayList<>();

    public void addEvaluation(CourseEvaluation eval) {
        evaluations.add(eval);
    }

    public List getEvaluationsByCourse(String courseId) {
        List result = new ArrayList<>();
        for (CourseEvaluation e : evaluations) {
            if (e.getCourseId().equals(courseId)) {
                result.add(e);
            }
        }
        return result;
    }
}
  

public double getAverageRating(String courseId) {
    List courseEvals = getEvaluationsByCourse(courseId);
    if (courseEvals.isEmpty()) return 0.0;

    int sum = 0;
    for (CourseEvaluation e : courseEvals) {
        sum += e.getRating();
    }
    return (double) sum / courseEvals.size();
}
  

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

public Map analyzeComments(String courseId) {
    List courseEvals = getEvaluationsByCourse(courseId);
    Map wordCount = new HashMap<>();
    String[] positiveWords = {"好", "棒", "清楚", "喜欢"};
    String[] negativeWords = {"难", "差", "不懂", "混乱"};

    for (CourseEvaluation e : courseEvals) {
        String comment = e.getComment();
        for (String word : positiveWords) {
            if (comment.contains(word)) {
                wordCount.put(word, wordCount.getOrDefault(word, 0) + 1);
            }
        }
        for (String word : negativeWords) {
            if (comment.contains(word)) {
                wordCount.put(word, wordCount.getOrDefault(word, 0) + 1);
            }
        }
    }
    return wordCount;
}