How to convert int Array to JSON String in Android?

Question

I expected to find this question around, but I couldn't. Maybe I'm Googling the wrong thing.

I have a primitive integer array ( int[] ), and I want to convert this into a String , that is "JSON-Parseable", to be converted back to the same int[] .

What have I tried :

I tried this code :

// int[] image_ids_primitive = ...    

JSONArray mJSONArray = new JSONArray(Arrays.asList(image_ids_primitive));
String jSONString = mJSONArray.toString();
Prefs.init(getApplicationContext());
Prefs.addStringProperty("active_project_image_ids", jSONString);
// Note: Prefs is a nice Class found in StackOverflow, that works properly. 

When I printed the jSONString variable, it has the value : ["[I@40558d08"]

whereas, I expected a proper JSON String like this : {"1" : "424242" , "2":"434343"} not sure about the quotation marks, but you get the idea.

The reason I want to do this :

I want to keep track of local images (in drawable folder), so I store their id's in the int array, then I want to store this array, in the form of a JSON String, which will be later parsed by another activity. And I know I can achieve this with Intent extras. But I have to do it with SharedPreferences.

Thanks for any help!

Answer 1

You don't have to instantiate the JSONArray with Arrays.asList. It can take a normal primitive array.

Try JSONArray mJSONArray = new JSONArray(image_ids_primitive);

If you are using an API level below 19, one easy method would just be to loop over the int array and put them.

JSONArray mJSONArray = new JSONArray();

for(int value : image_ids_primitive)
{
    mJSONArray.put(value);
}

Source: Android Developers doc

Answer 2

Try this way

int [] arr = {12131,234234,234234,234234,2342432};

        JSONObject jsonObj = new JSONObject();

        for (int i = 0; i < arr.length; i++) {
            try {
                jsonObj.put(""+(i+1), ""+arr[1]);
            } catch (Exception e) {
            }
        }
        System.out.println("JsonString : " + jsonObj.toString());

Answer 3

// If you wants the data in the format of array use JSONArray.
    JSONArray jsonarray = new JSONArray();
    //[1,2,1,] etc..
    for (int i = 0; i < data.length; i++) {
        jsonarray.put(data[i]);
    }
    System.out.println("Prints the Json Object data :"+jsonarray.toString());
    JSONObject jsonObject=new JSONObject();
    // If you want the data in key value pairs use json object.
    // i.e {"1":"254"} etc..
    for(int i=0;i<data.length;i++){
        try {
            jsonObject.put(""+i, data[i]);
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    System.out.println("Prints the Json Object data :"+jsonObject.toString());

Answer 4

If you want a JSON array and not necessarily an object, you can use JSONArray .

Alternatively, for a quick hack:

System.out.println(java.util.Arrays.toString(new int[]{1,2,3,4,5,6,7}));

prints out

[1, 2, 3, 4, 5, 6, 7] 

which is valid JSON. If you want anything more complicated than that, obviously JSONObject is your friend.

Answer 5

itertate this through the int array and you will get the json string

JSONStringer img = null ;

  img = new JSONStringer() .object() .key("ObjectNAme")
                  .object() .key("something").value(yourIntarrayAtIndex0)
                  .key("something").value(yourIntarrayAtIndex1) .key("something").value(yourIntarrayAtIndex2)
                  .key("something").value(yourIntarrayAtIndex3) 
                  .endObject() .endObject();

                  String se = img.toString();

Here se is your json string in string format

Answer 6

This code will achieve what you are after...

int index = 0;
final int[] array = { 100, 200, 203, 4578 };
final JSONObject jsonObject = new JSONObject();
try {
    for (int i : array) {
        jsonObject.put(String.valueOf(index), String.valueOf(i));
        index++;
    }
} catch (JSONException e) {
    e.printStackTrace();
}                       
Log.d("YOUR_TAG", jsonObject.toString());

This will give you {"3" : "203", "2" : "200", "1": "100", "4": "4578"} as a string.

Not exactly sure why its not in the exact order, but sorting by a key is quite easy.