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：
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countWays(JsonNode node, String question) 方法:
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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
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确保已添加 Jackson 依赖到项目中。可以使用 maven 或 gradle 添加依赖。
Maven:
<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.13.0</version> <!-- 使用最新版本 --> </dependency>
Gradle:
implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.0' // 使用最新版本
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JSON结构必须有效，否则解析可能会失败。
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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。
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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。
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