java - 如何使用文本文件递归制作树？

Question

我有一个包含以下内容的文本文件:

1Would you like Food or Drink? Enter either y for option one or n for the other.
1Would you like Hot food y/n?
Tomato Soup
Chicken salad
1Would you like a Fizzy drink? y/n?
Pepsi
Water

以“1”开头的句子表示一个问题。这些线是为树预先排序的。我想使用缓冲阅读器递归地生成一个方法来配合它。我希望树看起来像下面这样:

Would you like Food or Drink? Enter either y for option one or n for the other.
    Would you like Hot food y/n?
        Tomato Soup
        Chicken Salad
   Would you like a Fizzy drink? y/n?
        Pepsi
        Water

我正在努力制定该方法，我相信基本情况是新行是答案而不是问题。到目前为止我有这个:

public static void fromPreOrder(BufferedReader br) throws IOException {
    String line = br.readLine();
    if (!line.startsWith("*")) {
        return;
    }
    TreeNode fromPreOrderTree = new TreeNode(line);
    line = br.readLine();
    if (line.startsWith("*"));
    fromPreOrderTree.left = new TreeNode(line);
    fromPreOrder(br);

}

但它没有按预期工作。

Answer 1

代码

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

class TreeNode {
    TreeNode left;
    TreeNode right;
    String text;
}

public class SO {

    public static void main(final String... args) throws IOException {
        try (BufferedReader br = new BufferedReader(new FileReader("data.txt"))) {
            TreeNode node = readNode(br);
        }
    }

    public static TreeNode readNode(BufferedReader reader) throws IOException {
        String text = reader.readLine();
        if (text.charAt(0) == '1') {
            TreeNode node = new TreeNode();
            node.text = text.substring(1);
            node.left = readNode(reader);
            node.right = readNode(reader);
            return node;
        } else {
            TreeNode node = new TreeNode();
            node.text = text;
            return node;
        }
    }
}

说明

对于每个节点，如果它以 1 开头，我们读取它和 2 个子节点，否则我们只读取当前节点。