Android 应用程序和数据库通信：JSON 解析和列表视图

Question

I am developing an app that communicates with Database, to retrieve values. I am using PHP for the Backend, and developing on Android Studio, using the Volley Library .

My problem is, the values that I need to send are multiple records of a table, each with four columns, for example name, age, department, and country. I am using JSON to encode these values, but I need help with how to proceed. Should I use JSON encoded 2D Arrays? if so, how to make use PHP to construct this array, as there can be variable numbers of rows.

Also, How to parse that JSON Object/Array in Android (Java)?

As of now, this is my progress: JSON Output in browser:

{"name0":"ABC","age0":"25","department0":"Medical","country0":"XYZ","name1":"DEF","age1":"26","department1":"Engg.","country1":"XYZ"}

Here, I named each "key" of JSON using a Loop in PHP, and encoded as JSON Object. But Having Difficulty in displaying this in Android. I have used a XML layout with 4 textviews, and LISTVIEW in the main Activity XML File.

Answer 1

I would suggest a different json structure for encoding. Yours will get messy pretty quick if there are a lot of records. For example you would have name0 , name1 , ... nameN . It would be better to make an array like so:

[
    {
        "name" : "ABC",
        "age" : 25,
        "department" : "Medical",
        "country" : "XYZ"
    },
    {
        ...
    }
]

Notice that there are no indices concatenated to your keys. You can get the index based on the json object node's position in the array if you need it.

As for parsing it in Android, you can refer to the documentation . There is a Json parser that comes with the SDK so all you need to do is read in your string as a json array and iterate over its object nodes as needed.

For example

String jsonResponse = " ... "; // whatever the php backend gives you when you make a call to the endpoint
JSONArray arr = new JSONArray(jsonResponse);
for (int i=0; i<arr.length(); i++) {
    JSONObject obj = arr.get(i);
    String name = obj.getString("name");
    ...
}