java - 提取特定的json数组元素，比较所有数组元素

我有以下格式的json对象。

[
    {
        "StudentID": 1,
        "StudentMarks": [
            {
                "StudentID": 1,
                "English": 1500000,
                "Maths": 15,
                "Science": 15,
                "History": 10,
                "TestID": 1,
                "Date": "2018-01-29T14:38:11.01"
            },
            {
                "StudentID": 1,
                "English": 155,
                "Maths": 1578,
                "Science": 15,
                "History": 10,
                "TestID": 2,
                "Date": "2018-01-29T14:38:11.01"
            },
            {
                "StudentID": 1,
                "English": 155,
                "Maths": 15,
                "Science": 150,
                "History": 10,
                "TestID": 3,
                "Date": "2018-01-29T14:38:11.01"
            },
            {
                "StudentID": 1,
                "English": 150,
                "Maths": 15,
                "Science": 15,
                "History": 10,
                "TestID": 6,
                "Date": "2018-01-29T14:38:11.01"
            },
            {
                "StudentID": 1,
                "English": 155,
                "Maths": 1578,
                "Science": 15,
                "History": 10,
                "TestID": 7,
                "Date": "2018-01-29T14:38:11.01"
            }
        ]
    },
    {
        "StudentID": 2,
        "StudentMarks": [
            {
                "StudentID": 2,
                "English": 155,
                "Maths": 151,
                "Science": 15,
                "History": 1025,
                "TestID": 4,
                "Date": "2018-01-29T14:38:11.01"
            },
            {
                "StudentID": 2,
                "English": 1551,
                "Maths": 15,
                "Science": 15,
                "History": 100,
                "TestID": 5,
                "Date": "2018-01-29T14:38:11.01"
            },
            {
                "StudentID": 2,
                "English": 1,
                "Maths": 1,
                "Science": 15,
                "History": 10,
                "TestID": 8,
                "Date": "2018-01-29T14:38:11.01"
            }
        ]
    }
]

在此，我需要在android自定义列表视图中列出学生ID和最新的测试标记，

要提取每个学生证，我正在使用

JSONArray myListsAll= new JSONArray(jsonStr);
for(int i=0;i<myListsAll.length();i++)
{
    JSONObject c= (JSONObject) myListsAll.get(i);
    History= c.getString("History");
    Science= c.getString("Science");
    Maths= c.getString("Maths");
    English= c.getString("English");
}

但是我想要学生证并标记最新测试的详细信息。我想到从“ StudentMarks”中获取最大“ TestId”的数组元素。怎么做？

最佳答案

假设您能够遍历并且使用下面的代码行获取所有StudentMarks

JSONArray myListsAll= new JSONArray(jsonStr);
for(int i=0;i<myListsAll.length();i++)
{
    JSONObject obj= (JSONObject) myListsAll.get(i);
    History= obj.getString("History");
    ...
}

然后，IMO，您可以在获得最大TestId时存储值，并为获得最大TestId，可以将其初始化为最小值，每当获得更大的值时，将所有值覆盖为最新值。

JSONArray myListsAll= new JSONArray(jsonStr);
int test_id = Integer.MIN_VALUE;
for(int i=0;i<myListsAll.length();i++)
{
    JSONObject obj= (JSONObject) myListsAll.get(i);
    int curTestId = obj.getInt("TestID");
    if (test_id < curTestId)
    {
       History= obj.getString("History");
       Science= obj.getString("Science");
       Maths= obj.getString("Maths");
       English= obj.getString("English");
       test_id = curTestId;
    }
}

System.out.print("Maximum Test Id for this student :" + test_id );

关于java - 提取特定的json数组元素，比较所有数组元素，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/48519498/