How to remove JSONArray element using Java

Question

My JsonArray is

[{
"Id": null,
"Name": "One New task",
"StartDate": "2010-02-03T05:30:00",
"EndDate": "2010-02-04T05:30:00",
"Duration": 1,
"DurationUnit": "d",
"PercentDone": 0,
"ManuallyScheduled": false,
"Priority": 1,
"parentId": 8,
"index": 0,
"depth": 3,
"checked": null },{
"Id": null,
"Name": "New task",
"StartDate": "2010-02-04T05:30:00",
"EndDate": "2010-02-04T05:30:00",
"Duration": 0,
"DurationUnit": "d",
"PercentDone": 0,
"ManuallyScheduled": false,
"Priority": 1,
"parentId": 8,
"index": 1,
"depth": 3,
"checked": null }]

Now from this JsonArray I want to remove Id, ManuallyScheduled, checked,

I tried using jsonArray.remove(1) and also jsonArray.discard("Id") in JAVA. but nothing happens. what am I doing wrong to remove array items?

I am using JAVA as my technology.

Wattage

Answer 1

What you have there is an array of objects. Therefore you'll have to loop through the array and remove the necessary data from each object, e.g.

for (int i = 0, len = jsonArr.length(); i < len; i++) {
    JSONObject obj = jsonArr.getJSONObject(i);
    // Do your removals
    obj.remove("id");
    // etc.
}

I've assumed you're using org.json.JSONObject and org.json.JSONArray here, but the principal remains the same whatever JSON processing library you're using.

If you wanted to convert something like [{"id":215},{"id":216}] to [215,216] you could so something like:

JSONArray intArr = new JSONArray();
for (int i = 0, len = objArr.length(); i < len; i++) {
    intArr.put(objArr.getJSONObject(i).getInt("id"));
}

Theophrastus

Glad to hear it :-) You could always extend JSONArray and add a removeData(String... keys) method or something similar if this was something you wanted to do regularly. – Theophrastus

one more question to you.. How can i just pass the value to JSONArray in java. like I am having jsonArray of form [{"id":215},{"id":216}] but i want to convert my jsonArray to [215,216] is there any way to do so ?? how can i achieve this. – Wattage

You could do this manually, I'll update my answer to show how to do this. – Theophrastus

Hi I am having the same problem I am receiving the date in format of 2012-01-30T00:00:00 so how can I assign it to my Date variable startDate in JAVA pojo class. – Wattage

I should think you'll have to use .getString("date") and then manually parse the String into a Date using something like SimpleDateFormat. – Theophrastus

how to parse the date String i received from String to Date using SimpleDateFormate ?? Do you have any idea.. My String Date is 2012-01-30T00:00:00 – Wattage

If you don't mind about the time (i.e. it's always 00:00:00) then you could just remove that bit and then parse. e.g. SimpleDateFormat sdf = new SimpleDateFormat("YY-MM-DD"); Date d = sdf.parse(str.split("T")[0]); Here's the SimpleDateFormat javadoc. – Theophrastus

I tried to use your solution but don't know my sysout is not working I am not able to parse using SimpleDateFormat sdf = new SimpleDateFormat("YY-MM-DD"); Date d = sdf.parse(jsonObject.getString("StartDate").split("T")[0]); my java console is not giving any error and the line not executing – Wattage

Try yyyy-MM-dd for the SimpleDateFormat pattern. – Theophrastus

Answer 2

This is useful sometimes in android when you want to use the json structure directly.

Notice that I only use this when I'm handling JSONObject inside the array.

public static JSONArray remove(final int idx, final JSONArray from) {
    final List<JSONObject> objs = asList(from);
    objs.remove(idx);

    final JSONArray ja = new JSONArray();
    for (final JSONObject obj : objs) {
        ja.put(obj);
    }

    return ja;
}

public static List<JSONObject> asList(final JSONArray ja) {
    final int len = ja.length();
    final ArrayList<JSONObject> result = new ArrayList<JSONObject>(len);
    for (int i = 0; i < len; i++) {
        final JSONObject obj = ja.optJSONObject(i);
        if (obj != null) {
            result.add(obj);
        }
    }
    return result;
}

Accouter

Why add to a list<> and not directly add to a new JSONArray? – Iffy

yes, you can do that. I have the unoptimized version because I already had the method asList for convenience. – Accouter

Answer 3

The following method will find the object in an array with the matching id, then return the filtered array.

public JSONArray removeObject(JSONArray array, String id) throws JSONException {
    for (int i = 0; i < array.length(); i++) {
        JSONObject obj = array.getJSONObject(i);
        if (obj.getString("ID").equals(id)) {
            array.remove(i);
            //  Toast.makeText(this, "ENCONTRADO", Toast.LENGTH_SHORT).show();
        }
    }
    return array;
}

Piece