java - 使用 GSON 计算 JSON 响应中的 id

Question

我从 REST 服务收到以下 JSON 响应 -

[
   {
      "id":"cls102",
      "name":"Class X",
      "students":[
         {
            "total-students":38,
            "present-students":35
         }
      ]
   },
   {
      "id":"cls202",
      "name":"Class XI",
      "students":[
         {
            "total-students":42,
            "present-students":38
         }
      ]
   }
]

我的目标是获取元素id的总数。我创建了如下所示的模型类 -

public class ClassRoom {
    private String id;
    private String name;
    private Student[] students;
    // Getter and Setter are not put here
}

import com.google.gson.annotations.SerializedName;

public class Student {
    @SerializedName("total-students")
    private int totalStudents;
    @SerializedName("present-students")
    private int presentStudents;
    // Getter and Setter are not put here
}

现在我的测试类正在以以下方式调用 Gson -

Gson gson = new GsonBuilder().create();
ClassRoom agents = gson.fromJson(jsonRepsone, ClassRoom.class);

现在，如何进一步进行？

Answer 1

您需要执行类似的操作，因为您的 JSON 表示 ClassRoom 对象的数组。

Gson gson = new GsonBuilder().create();
ClassRoom[] agents = gson.fromJson(jsonRepsone, ClassRoom[].class);

//Gives the no. of ClassRoom objects, which corresponds to the no.of `id`s
System.out.println(agents.length);