本文介绍如何使用Java和JSON数据，计算一个基于问题的问卷调查中所有可能的路径数量。通过递归方法，我们可以遍历JSON结构，确定从起始问题到所有可能的结束点的路径总数。本文提供详细的代码示例和解释，帮助你理解并实现该算法，从而更好地分析和管理问卷调查数据。
理解问题结构
问卷调查的结构以JSON格式存储，其中每个问题对应一个JSON对象。该对象包含问题的文本以及可能的答案。每个答案又指向下一个问题，形成一个问题链。当答案指向一个以"0"开头的字符串时，表示问卷调查的结束。
例如：
{
"What is your marital status?": {
"Single": "Are you planning on getting married next year?",
"Married": "How long have you been married?"
},
"Are you planning on getting married next year?": {
"Yes": "0 Thanks for your answers! We hope that you will build a cool family!",
"No": "0 Thanks for your answers! Who knows, maybe you'll find someone significant in your life!"
},
"How long have you been married?": {
"Less than a year": "0 Thanks for your answers! We hope that you will celebrate your one year anniversary soon!",
"More than a year": "Have you celebrated your one year anniversary?"
},
"Have you celebrated your one year anniversary?": {
"Yes": "0 Wow, cool! Keep it up! Thanks for your answers.",
"No": "0 We think you should fix it next time! Thanks for your answers!"
}
}递归计算路径数
要计算所有可能的路径数，可以使用递归方法。递归函数将遍历JSON结构，并对每个答案递归调用自身。当达到一个结束点时，递归将返回1。否则，它将返回所有子路径数的总和。
以下是Java代码示例，使用com.fasterxml.jackson.databind库来解析JSON：
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
import java.util.concurrent.atomic.AtomicInteger;
public class QuizPathCounter {
public static int countWays(JsonNode node, String question) {
JsonNode answers = node.get(question);
if (answers == null) {
return 1; // 达到结束点
}
AtomicInteger ways = new AtomicInteger();
answers.fields().forEachRemaining(answer ->
ways.addAndGet(countWays(node, answer.getValue().asText())));
return ways.get();
}
public static void main(String[] args) throws IOException {
String jsonString = "{" +
" \"What is your marital status?\": {" +
" \"Single\": \"Are you planning on getting married next year?\"," +
" \"Married\": \"How long have you been married?\"" +
" }," +
" \"Are you planning on getting married next year?\": {" +
" \"Yes\": \"0 Thanks for your answers! We hope that you will build a cool family!\"," +
" \"No\": \"0 Thanks for your answers! Who knows, maybe you'll find someone significant in your life!\"" +
" }," +
" \"How long have you been married?\": {" +
" \"Less than a year\": \"0 Thanks for your answers! We hope that you will celebrate your one year anniversary soon!\"," +
" \"More than a year\": \"Have you celebrated your one year anniversary?\"" +
" }," +
" \"Have you celebrated your one year anniversary?\": {" +
" \"Yes\": \"0 Wow, cool! Keep it up! Thanks for your answers.\"," +
" \"No\": \"0 We think you should fix it next time! Thanks for your answers!\"" +
" }" +
"}";
ObjectMapper mapper = new ObjectMapper();
JsonNode node = mapper.readTree(jsonString);
int totalPaths = countWays(node, "What is your marital status?");
System.out.println("Total possible paths: " + totalPaths); // 输出: Total possible paths: 8
}
}代码解释：
-
countWays(JsonNode node, String question) 方法:
- 接受 JSON 节点和当前问题作为输入。
- node.get(question) 获取当前问题对应的答案节点。
- 如果 answers 为 null，表示到达终点，返回 1。
- 使用 AtomicInteger 来累加所有路径的数量，因为 forEachRemaining 需要一个线程安全的方式来更新计数器。
- answers.fields().forEachRemaining 遍历所有答案。
- 对于每个答案，递归调用 countWays 方法，并将返回的路径数加到 ways 中。
- 最后返回 ways 的值，即从当前问题开始的所有可能路径数。
-
main 方法:
- 定义包含问卷调查数据的 JSON 字符串。
- 创建 ObjectMapper 实例来解析 JSON 字符串。
- 使用 mapper.readTree(jsonString) 将 JSON 字符串解析为 JsonNode 对象。
- 调用 countWays 方法，以起始问题 "What is your marital status?" 作为参数。
- 打印结果。
注意事项
-
确保已添加 Jackson 依赖到项目中。可以使用 Maven 或 Gradle 添加依赖。
Maven:
com.fasterxml.jackson.core jackson-databind 2.13.0 Gradle:
implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.0' // 使用最新版本
JSON结构必须有效，否则解析可能会失败。
递归深度过大可能导致栈溢出。对于非常复杂的问卷调查，可能需要考虑使用迭代方法代替递归。
此方法假设所有以 "0" 开头的字符串表示结束点。 可以根据实际情况修改判断逻辑。
总结
通过使用递归方法，我们可以有效地计算JSON驱动的问卷调查中所有可能的路径数。该方法可以帮助我们更好地理解问卷调查的结构，并分析用户在问卷调查中的行为模式。根据实际需求，可以对代码进行扩展，例如记录每个路径的具体问题和答案，或者根据路径的长度进行加权计算。
