java - JSONArray 中的唯一 JSONObject

Question

我有一个 JSONArray，其中包含一组 JSONObject。从

获取唯一 JSONObject 的最佳算法是什么

"lessaon_plan_data": [
      {
        "lessonplan_marks": 100,
        "lessonplan_name": "wdwd",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 50,
        "lessonplan_name": "ewewd",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 8,
        "lessonplan_name": "qwefqwef",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 20,
        "lessonplan_name": "qwefqwef",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 4,
        "lessonplan_name": "qwefqwef",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 8,
        "lessonplan_name": "qwefqwef",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 20,
        "lessonplan_name": "qwefqwef",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 4,
        "lessonplan_name": "qwefqwef",
        "lessonplan_subject": "Maths"
      },
      {
        "lessonplan_marks": 8,
        "lessonplan_name": "qwefqwef",
        "lessonplan_subject": "Maths"
      }
    ]

我尝试过的是:

private JSONArray removeDuplicate(JSONArray rubricReportArray) {
    Log.e("MethodEntered", "success");
    JSONArray tempArray = new JSONArray();
    try {
        JSONObject tempStudentObj = null;
        for (int i = 0; i < rubricReportArray.length(); i++) {
            JSONObject studentObj = rubricReportArray.getJSONObject(i);


            tempStudentObj = new JSONObject();
            tempStudentObj.put("student_name", studentObj.getString("student_name"));
            tempStudentObj.put("lessonplan_name", studentObj.getString("lessonplan_name"));
            tempStudentObj.put("student_id", studentObj.getString("student_id"));
            tempStudentObj.put("lessonplan_subject", studentObj.getString("lessonplan_subject"));
            tempStudentObj.put("student_marks", studentObj.getString("student_marks"));
            tempStudentObj.put("lessonplan_class", studentObj.getString("lessonplan_class"));


            JSONArray duplicateArray = studentObj.getJSONArray("lessaon_plan_data");
            JSONArray uniqueArray = new JSONArray();
            Map<String,String> uniqueMap = new HashMap<>();

            for (int j = 0; j < duplicateArray.length(); j++) {
                boolean flag = false;
                String lessonMarks = duplicateArray.getJSONObject(j).getString("lessonplan_marks");
                String lessonName = duplicateArray.getJSONObject(j).getString("lessonplan_name");
                String lessonSubject = duplicateArray.getJSONObject(j).getString("lessonplan_subject");
                for (int k = j + 1; k < duplicateArray.length() - 1; k++) {
                    String currentLessonMarks = duplicateArray.getJSONObject(k).getString("lessonplan_marks");
                    String currentLessonName = duplicateArray.getJSONObject(k).getString("lessonplan_name");
                    String currentLessonSubject = duplicateArray.getJSONObject(k).getString("lessonplan_subject");
                    if (!lessonSubject.equalsIgnoreCase(currentLessonSubject)) {
                        uniqueArray.put(duplicateArray.getJSONObject(j));
                        break;
                    } else if (!lessonName.equalsIgnoreCase(currentLessonName)) {
                        flag = false;
                        uniqueArray.put(duplicateArray.getJSONObject(j));
                        break;
                    } else {
                        if (!lessonMarks.equalsIgnoreCase(currentLessonMarks)) {
                            flag = true;
                        }
                    }
                }
                if (flag) {
                    uniqueArray.put(duplicateArray.getJSONObject(j));
                }
                //Log.e("Unique JSON",set.toString());
            }
            tempStudentObj.put("lessaon_plan_data", uniqueArray);
            Log.e("TempStudent", tempStudentObj.toString());
            tempArray.put(tempStudentObj);

        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

    return tempArray; //assign temp to original

}

我得到了独特的元素，其中有独特的主题和类(class)。但是当相同的类(class)和相同的科目但分数不同时，问题就来了。

如何从中获取唯一的 JSONObject 并将其存储在新的或替换在同一个 JSONArray 中？我已经尝试了 stackoverflow 中的大部分解决方案。但在我的情况下没有任何作用。请帮忙。提前致谢

Answer 1

目前还不清楚您做了什么或如何存储对象。

但是如果您还没有这样做，那么我的建议是使用仅维护唯一对象而不是数组的 Java 集合。

所以是 HashSet、TreeSet 或类似的东西。那么你可以；

1. 在插入之前，检查集合在插入之前是否存在该对象，然后根据需要进行处理。
2. 插入现有对象并用新对象替换现有对象

请记住，对象的比较需要您在类中创建自己的 equals() 比较(当然您还需要重写 hashcode() )

另请参阅:Prevent duplicate entries in arraylist

更新:

我使用 Gson 来解码我的 json，下面只给了我 3 个唯一的条目；

Gson gson = new Gson();
Type listType = new TypeToken<HashSet<LessonPlan>>(){}.getType();
Set<LessonPlan> lpList = new Gson().fromJson(json, listType);

类(class)计划类(class)

public class LessonPlan {
    private int lessonplan_marks;
    private String lessonplan_name;
    private String lessonplan_subject;

    public int getLessonplan_marks() {
        return lessonplan_marks;
    }

    public void setLessonplan_marks(int lessonplan_marks) {
        this.lessonplan_marks = lessonplan_marks;
    }

    public String getLessonplan_name() {
        return lessonplan_name;
    }

    public void setLessonplan_name(String lessonplan_name) {
        this.lessonplan_name = lessonplan_name;
    }

    public String getLessonplan_subject() {
        return lessonplan_subject;
    }

    public void setLessonplan_subject(String lessonplan_subject) {
        this.lessonplan_subject = lessonplan_subject;
    }

    public LessonPlan() {


    }

    public String toString()
    {
        return "Name: " + this.getLessonplan_name() + " subject: " + this.getLessonplan_subject() + " marks: " + this.getLessonplan_marks();
    }


    public boolean equals(Object obj)
    {
        if (obj instanceof LessonPlan)
        {
            LessonPlan other = (LessonPlan)obj;
            if (other.getLessonplan_name().equals(this.getLessonplan_name()) && other.getLessonplan_subject().equals(this.getLessonplan_subject()))
                return true;
            else
                return false;
        }
        else
            return false;
    }

    public int hashCode()
    {
        return this.getLessonplan_name().hashCode() + this.getLessonplan_subject().hashCode();
    }

当然，这样做我无法控制保留哪些对象。