Java - 文本文件 - 在某些字符串之间读取

Question

在过去的 20 个小时里，我试图解决以下问题，所以在开始考虑跳出窗外之前我想，我最好在这里寻求帮助:

I have a text file with following content:
ID
1
Title
Men and mice
Content
Lenny loves kittens
ID
2
Title
Here is now only the Title of a Book
ID
3
Content
Here is now only the Content of a Book

如您所见，问题在于 id 后面要么有标题和内容，要么 id 后面只有标题。我想创建包含 ID 值(例如 1)以及相应的标题值和/或内容值的文本文件。

我取得的最好成绩是三个列表。一种带有 id 值，一种带有标题值，一种带有内容值。但实际上并没有什么用，因为 id、content 和 title 之间的信息丢失了。

我非常感谢您的支持。

Answer 1

因此，您想用三个字段填充类的集合。

class Data {
    int id;
    String title;
    String content;

    // helper method to read a file and return a list.
    public static List<Data> readAll(String filename) throws IOException {
        // List we will return.
        List<Data> ret = new ArrayList<Data>();
        // last value we added.
        Data last = null;
        // Open a file as text so we can read the lines.
        // us try-with-resource so the file is closed when we are done.
        try (BufferedReader br = new BufferedReader(new FileReader(filename))) {
            // declare a String and use it in a loop.
            // read line and stop when we get a null
            for (String line; (line = br.readLine()) != null; ) {
                // look the heading.
                switch (line) {
                    case "ID":
                        // assume ID is always first
                        ret.add(last = new Data());
                        // read the next line and parse it as an integer
                        last.id = Integer.parseInt(br.readLine());
                        break;

                    case "Title":
                        // read the next line and save it as a title
                        last.title = br.readLine();
                        break;
                    case "Content":
                        // read the next line and save it as a content
                        last.content = br.readLine();
                        break;
                }
            }
        }
        return ret;
    }
}

注意:唯一重要的字段是 ID。内容和标题是可选的。

要将 20 小时减少到 5 分钟，您需要大量练习。