將Gson數組轉換為Arraylist

Question

我已經看到了很多這樣的問題，但是我仍然無法解決這個問題。

我從服務器收到了一個json，其中包含多個gson數組。

我如何反序列化來自服務器的響應以滿足這些模型。

主題模型：

public class Subject {  
    public int SubjectId;
    public String SubjectName;
    public ArrayList Courses;
}

課程模式：

public class Course {
    public String CourseName;
    public String CourseDescription;
    public int CourseId;
    public int Subject_SubjectId;
}

編輯這是服務器返回的內容：我使用了Google Chrome Extension PostMan來檢索它。

這是實際的

{
"StudentSubject": [
    {
        "SubjectId": 1059,
        "SubjectName": "Accounting",
        "Student_CourseId": 0,
        "UniversitySubjectId": 0,
        "Courses": [
            {
                "CourseId": 1091,
                "CourseName": "ACCT 101",
                "CourseDescription": "",
                "Subject_SubjectId": 1059
            },
            {
                "CourseId": 1092,
                "CourseName": "ACCT 111",
                "CourseDescription": "",
                "Subject_SubjectId": 1059
            },
            {
                "CourseId": 1093,
                "CourseName": "ACCT 115",
                "CourseDescription": "Financial Accounting Foundations",
                "Subject_SubjectId": 1059
            }
        ]
     },
    {
        "SubjectId": 1060,
        "SubjectName": "Mathematics",
        "Student_CourseId": 0,
        "UniversitySubjectId": 0,
        "Courses": [
            {
                "CourseId": 1094,
                "CourseName": "MATH 100",
                "CourseDescription": "Fundamentals of Mathematics",
                "Subject_SubjectId": 1060
            },
            {
                "CourseId": 1095,
                "CourseName": "MATH 101",
                "CourseDescription": "Introduction to Analysis I",
                "Subject_SubjectId": 1060
            },
            {
                "CourseId": 2126,
                "CourseName": "MATH 200",
                "CourseDescription": "Multivariate Calculus",
                "Subject_SubjectId": 1060
            },
            {
                "CourseId": 2132,
                "CourseName": "MATH 102",
                "CourseDescription": "Introduction to Analysis II",
                "Subject_SubjectId": 1060
            }
        ]
    },
    {
        "SubjectId": 1069,
        "SubjectName": "Bioscience & Biotechnology",
        "Student_CourseId": 0,
        "UniversitySubjectId": 0,
        "Courses": [
            {
                "CourseId": 1109,
                "CourseName": "BIO 100",
                "CourseDescription": "Applied Cells, Genetics & Physiology",
                "Subject_SubjectId": 1069
            },
            {
                "CourseId": 2123,
                "CourseName": "BIO 124",
                "CourseDescription": "Evolution & Organismal Diversity",
                "Subject_SubjectId": 1069
            }
        ]
    },
    {
        "SubjectId": 2084,
        "SubjectName": "Computer Science",
        "Student_CourseId": 0,
        "UniversitySubjectId": 0,
        "Courses": [
            {
                "CourseId": 2137,
                "CourseName": "CS 101",
                "CourseDescription": "",
                "Subject_SubjectId": 2084
            }
        ]
    },
    {
        "SubjectId": 2086,
        "SubjectName": "Business Statistics",
        "Student_CourseId": 0,
        "UniversitySubjectId": 0,
        "Courses": [
            {
                "CourseId": 2141,
                "CourseName": "STAT 101",
                "CourseDescription": "",
                "Subject_SubjectId": 2086
            }
        ]
    }
  ]
}

Answer 1

嘗試

Type listType = new TypeToken<List<Subject>>() {}.getType();
List<Subject> subjects = new Gson().fromJson(yourJsonString, listType);

您的Subject類應該看起來像這樣

class Subject {  
  int SubjectId;
  String SubjectName;
  List<Course> Courses;
}

Answer 2

您的json根本無法驗證。

標簽必須位於" " ，並且=必須全部為:

使用http://www.jslint.com/檢查其他錯誤。

您嘗試對其進行的任何json解析都自然會失敗。

Answer 3

正如柏拉圖所提到的，Json字符串格式不正確，這是我用來測試您想要實現的概念的正確格式。

[{"SubjectId":"1059.0",
  "SubjectName":"Accounting",
  "Student_CourseId":"0.0",
  "UniversitySubjectId":"0.0",
  "Courses":[
        {"CourseId":"1091.0",
         "CourseName":"ACCT 101",
         "CourseDescription":"",
         "Subject_SubjectId":"1059.0"
         },
         {"CourseId":"1092.0",
         "CourseName":"ACCT 111",
         "CourseDescription":"",
         "Subject_SubjectId":"1059.0"
         }
        ]
 }]

這個gson庫可以使用后，

    Gson gson = new Gson();
    Subject[] subject = gson.fromJson(jsonString, Subject[].class);
    ArrayList<Course> course = subject[0].Courses;
    System.out.println(subject[0].SubjectId);
    System.out.println(course.get(0).CourseId);

當然，以上邏輯僅在Json格式正確，更正從服務器接收的json響應后才有效，然后才應該起作用。

希望這可以幫助！！！