java - 就像数组列表中的计数器不断返回 0

Question

我尝试对论坛主题进行类似的计数器。这是我的代码:

当点击like按钮时，它会将值插入数据库。

public void submitLike(ActionEvent e) {
    int count = 0;
    int newCount = count + 1;
    eForumLikeDislike amount = new eForumLikeDislike(userName,topicId,newCount);
    amount.likeCounter();
}

我插入的SQL语句就像点击时一样。

 public void SetUpLikeAmount() {
    int likes = 0;
    ArrayList <Integer> likeArray = new ArrayList <Integer>();
    for (int count = 0; count < likeArray.size();count++){
    // Set Up Database Source
    db.setUp("IT Innovation Project");
    String sql = "Select likeDislike_likes from forumLikeDislike WHERE topic_id = "
            + topicId + "";
    ResultSet resultSet = null;
    // Call readRequest to get the result
    resultSet = db.readRequest(sql);
    try {
        while (resultSet.next()) {
            likeArray.add(Integer.parseInt(resultSet.getString("likeDislike_likes")));
        }
        resultSet.close();
    } catch (Exception e) {
        System.out.println(e);
    }
    likes += likeArray.get(count);
    }
    jLabel_like.setText(Integer.toString(likes));
}

我尝试显示某个线程的总点赞数的方法。

public void SetUpLikeAmount() {
    int likes = 0;
    ArrayList <Integer> likeArray = new ArrayList <Integer>();
    for (int count = 0; count < likeArray.size();count++) {
        // Set Up Database Source
        db.setUp("IT Innovation Project");
        String sql = "Select likeDislike_likes from forumLikeDislike WHERE topic_id = "
                     + topicId + "";
        ResultSet resultSet = null;
        // Call readRequest to get the result
        resultSet = db.readRequest(sql);
        try {
            while (resultSet.next()) {
                likes = Integer.parseInt(resultSet.getString("likeDislike_likes"));
                likes += likeArray.get(count);
            }
            resultSet.close();
        } catch (Exception e) {
            System.out.println(e);
        }

    }
    jLabel_like.setText(Integer.toString(likes));
}

但是，金额一直返回0。有什么问题吗？我该如何修复它？
提前致谢。

Answer 1

如果您能够更改数据库设计，请这样做。具体来说，从表forumLikeDislike 中删除likeDislike_likes 字段。

完成后(或者即使没有)，您可以替换此查询，

Select likeDislike_likes 
from forumLikeDislike 
WHERE topic_id = the topicId variable you submit

使用此查询:

select count(*) likes
from forumLikeDislike 
WHERE topic_id = the topicId variable you submit

它将返回一行，其中包含您想要的答案。