Develop Reference

Build JSON Array from JSON Objects

I am running a loop where I am getting JSON Objects as inputs how do I append all these JSONObjects in a JSONArray?
The input is a JSONObject which contains a string based key value pair called "name" which I want to extract.
Following is what I tried, I am not able to append all of them together using the following code rather they are appearing one at a time.
List<String> hoi2 = new ArrayList();
if(input != null) {
hoi2.add(input.getString("name"));
}
System.out.println(hoi2);
Sample input format (Getting One Input at a time):
{"lon":77.5858225,"name":"bingo","lat":12.9171587}
{"lon":77.5858225,"name":"dingo","lat":12.9171587}
{"lon":77.5858225,"name":"lingo","lat":12.9171587}
Required result:
["bingo","dingo","lingo"]
My current result:
["bingo"]
["dingo"]
["lingo"]
Update:
I realised the issue my approach was wrong since my array was going blank after every input and re-writing it hence had to define a global variable.

For below code:
List<Integer> hoi2 = new ArrayList<Integer>();
for(int i=0; i<3; i++){
hoi2.add(i);
}
System.out.println(hoi2);
Output will be:
[0, 1, 2]
For below code:
for(int i=0; i<3; i++){
List<Integer> hoi2 = new ArrayList();
hoi2.add(i);
System.out.println(hoi2);
}
Output will be:
[0]
[1]
[2]

JSONArray jArray = new JSONArray();
for (int i = 0; i < docList.size(); i++) {
JSONObject json = new JSONObject(hoi2.get(i));
jArray.put(json);
}

here may post complete solution please refer it.
Code :
List<String> hoi2 = new ArrayList();
hoi2.add("{\"lon\":77.5858225,\"name\":\"bingo\",\"lat\":12.9171587}");
hoi2.add("{\"lon\":77.5858225,\"name\":\"dingo\",\"lat\":12.9171587}");
hoi2.add("{\"lon\":77.5858225,\"name\":\"lingo\",\"lat\":12.9171587}");
JSONArray jsonArray = new JSONArray();
try {
for (int i = 0; i < hoi2.size(); i++) {
JSONObject jsonObject = new JSONObject(hoi2.get(i));
System.out.print(jsonObject.getString("name"));
jsonArray.put(jsonObject.getString("name"));
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.print(jsonArray.toString());
output :
["bingo","dingo","lingo"]

new to json parsing - how to get an array within an array

from the following link , I need to get the value stored in "media".
Here is my code:
Content = Content.replace("jsonFlickrFeed(", "");
Content = Content.replace("})", "}");
jsonResponse = new JSONObject(Content);
JSONArray jsonMainNode = jsonResponse.optJSONArray("items"); // this works great!
But I can not access past "items"

You will have to loop through the JSON like this:
...
JSONArray jsonMainNode = jsonResponse.optJSONArray("items");
for (int i=0; i<jsonMainNode.length(); i++) {
String media = jsonMainNode.getJSONObject(i).getString("media");
}
This will loop through the images and return the value(s) in media.
In your case it should be something like this:
..
JSONArray jsonMainNode = jsonResponse.optJSONArray("items");
for (int i=0; i<jsonMainNode.length(); i++) {
JSONObject finalNode = jsonMainNode.getJSONObject(i);
JSONArray finalArray = finalNode.optJSONArray("media");
for (int j=0; j<finalArray.length(); j++) {
String m = finalArray.getJSONObject(j).getString("m");
}
}
...because there is another node inside the media node, called m.

Here is an example getting the tags string for each item in the JSONArray that you have:
for (int i = 0; i < jsonMainNode.length(); i++){
JSONObject jsonObject = jsonMainNode.getJSONObject(i);
String tags = jsonObject.getString("tags");
}
This will iterate through all JSONObjects that are in the array, and extract the tags field from each object.

JSONArray jsonMainNode = jsonResponse.optJSONArray("items"); // this works great!
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject item = (JSONObject) jsonMainNode.get(i);
JSONObject media = item.getJSONObject("media");
String valueMedia = media.getString("m");
Log.d("TAG", valueMedia);
}

Get JSON Array into strings.

I have a webservice which returns a JSON array in this format:
[{"imageid":"3","userid":"1","imagepath":"SLDFJNDSKJFN","filterid":"1","dateadded":"2014-05-06 21:20:18.920257","public":"t"},
{"imageid":"4","userid":"1","imagepath":"dsfkjsdkfjnkjdfsn","filterid":"1","dateadded":"2014-05-06 21:43:37.642748","public":"t"}]
I need to get all the attributes seperately? How would I do this?
I know how to do it with JSONObject if there is just 1 thing being returned, but how does it work when multiple items are returned?
Thanks

try {
JSONArray jArray = new JSONArray(jsonString);
String s = new String();
for (int i = 0; i < jArray.length(); i++) {
s = jArray.getJSONObject(i).getString("imageid").toString();
s = jArray.getJSONObject(i).getString("userid").toString();
}
} catch (JSONException je) {
}

Create an Object class with all variables, create a List for this Object, add all objects in your JSONArray to the list, use the one you need.
List<YourObject> objList = new ArrayList<YourObject>();
JSONArray a = new JSONArray(response);
int size = a.length();
for (int i=0 ; i<size ; i++){
JSONObject aa = a.getJSONObject(i);
String id = aa.getString("imageid");
String userid = aa.getString("userid");
String imagepath = aa.getString("imagepath");
String filterid = aa.getString("filterid");
String dateadded = aa.getString("dateadded");
String publicText = aa.getString("public");
YourObject obj = new YourObject(id,userid,imagepath,filterid,dateadded,publicText);
objList.add(obj);
}

So what you are having here is some JSON objects inside a JSON array.
What you want to do is this:
JSONArray array = ...;
for (int i = 0; i < array.length(); i++) {
JSONObject o = array.getJSONObject(i);
// Extract whatever you want from the JSON object.
}
I hope it helped.

You can use JSONArray to parse array of JSON response.
private void parseJsonArray(String response) {
try {
JSONArray array = new JSONArray(response);
for(int i=0;i<array.length();i++){
JSONObject jsonObject = array.getJSONObject(i);
String ImageId = jsonObject.getString("imageid");
Log.v("JSON Parser", "ImageId: "+ImageId);
}
} catch (Exception e) {
e.printStackTrace();
}
}

Android : HashMap is showing only last array item in a Listview field

I'm prsing information from a json file and showing data in a custom ListView. Now, I have an Array named authors. Where authors are multiple. But, in ListView I can only see the last authors name or last array item .
How can I show all items ? Here is my code
for (int index = 0; index < jsonArray.length(); index++)
{
HashMap<String, String> temp = new HashMap<String,String>();
JSONObject jsonObject = jsonArray.getJSONObject(index);
String topic = jsonObject.getString("topic");
String type = jsonObject.getString("type");
String title = jsonObject.getString("title");
String absData = jsonObject.getString("abstract");
JSONArray getAuthorsArray = new JSONArray(jsonObject.getString("authors"));
for(int a =0 ; a < getAuthorsArray.length(); a++){
JSONObject getJSonObj = (JSONObject)getAuthorsArray.get(a);
String authordName = getJSonObj.getString("name");
Log.e("Name", authordName);
temp.put(KEY_AUTHOR, authordName);
}
temp.put(KEY_TOPIC, topic);
temp.put(KEY_TYPE, type);
temp.put(KEY_TITLE, title);
temp.put(KEY_ABSTRACT,absData);
list.add(temp);
}
}
simpleAdapter = new SimpleAdapter(this, list, R.layout.abstract_items, from, new int[]{R.id.abTopic,R.id.abType,R.id.abTitle,R.id.SubTitle});
setListAdapter(simpleAdapter);

temp.put(KEY_AUTHOR, authordName);
That's probably why. You are iterating over the all authors but HashMap will override values and only the last one is being saveed.
As I understand you are getting back a JSON response with an array of JSONObject. Each JSONObject holding some info and a sub-JSONArray of associated authors.
The easiest approach could be just building ArrayList<JSONObject> and extending BaseAdapter implementing an adapter of your own. It's very easy. For large collections of data search on ViewHolder pattern, for optimization.

'HashMap<String, String> temp;
for (int index = 0; index < jsonArray.length(); index++)
{
temp = new HashMap<String,String>();
JSONObject jsonObject = jsonArray.getJSONObject(index);
String topic = jsonObject.getString("topic");
String type = jsonObject.getString("type");
String title = jsonObject.getString("title");
String absData = jsonObject.getString("abstract");
JSONArray getAuthorsArray = new JSONArray(jsonObject.getString("authors"));
for(int a =0 ; a < getAuthorsArray.length(); a++){
JSONObject getJSonObj = (JSONObject)getAuthorsArray.get(a);
String authordName = getJSonObj.getString("name");
Log.e("Name", authordName);
temp.put(KEY_AUTHOR, authordName);
}
temp.put(KEY_TOPIC, topic);
temp.put(KEY_TYPE, type);
temp.put(KEY_TITLE, title);
temp.put(KEY_ABSTRACT,absData);
list.add(temp);
}
}
simpleAdapter = new SimpleAdapter(this, list, R.layout.abstract_items, from, new int[]{R.id.abTopic,R.id.abType,R.id.abTitle,R.id.SubTitle});
setListAdapter(simpleAdapter);'
you declare the "HashMap"line in above the onstart values.it will help for you.

Convert Json Array to normal Java list

Is there a way to convert JSON Array to normal Java Array for android ListView data binding?

ArrayList<String> list = new ArrayList<String>();
JSONArray jsonArray = (JSONArray)jsonObject;
if (jsonArray != null) {
int len = jsonArray.length();
for (int i=0;i<len;i++){
list.add(jsonArray.get(i).toString());
}
}

If you don't already have a JSONArray object, call
JSONArray jsonArray = new JSONArray(jsonArrayString);
Then simply loop through that, building your own array. This code assumes it's an array of strings, it shouldn't be hard to modify to suit your particular array structure.
List<String> list = new ArrayList<String>();
for (int i=0; i<jsonArray.length(); i++) {
list.add( jsonArray.getString(i) );
}

Instead of using bundled-in org.json library, try using Jackson or GSON, where this is a one-liner. With Jackson, f.ex:
List<String> list = new ObjectMapper().readValue(json, List.class);
// Or for array:
String[] array = mapper.readValue(json, String[].class);

Maybe it's only a workaround (not very efficient) but you could do something like this:
String[] resultingArray = yourJSONarray.join(",").split(",");
Obviously you can change the ',' separator with anything you like (I had a JSONArray of email addresses)

Using Java Streams you can just use an IntStream mapping the objects:
JSONArray array = new JSONArray(jsonString);
List<String> result = IntStream.range(0, array.length())
.mapToObj(array::get)
.map(Object::toString)
.collect(Collectors.toList());

Use can use a String[] instead of an ArrayList<String>:
It will reduce the memory overhead that an ArrayList has
Hope it helps!
String[] stringsArray = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length; i++) {
parametersArray[i] = parametersJSONArray.getString(i);
}

I know that question is about JSONArray but here's example I've found useful where you don't need to use JSONArray to extract objects from JSONObject.
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
String jsonStr = "{\"types\":[1, 2]}";
JSONObject json = (JSONObject) JSONValue.parse(jsonStr);
List<Long> list = (List<Long>) json.get("types");
if (list != null) {
for (Long s : list) {
System.out.println(s);
}
}
Works also with array of strings

Here is a better way of doing it: if you are getting the data from API. Then PARSE the JSON and loading it onto your listview:
protected void onPostExecute(String result) {
Log.v(TAG + " result);
if (!result.equals("")) {
// Set up variables for API Call
ArrayList<String> list = new ArrayList<String>();
try {
JSONArray jsonArray = new JSONArray(result);
for (int i = 0; i < jsonArray.length(); i++) {
list.add(jsonArray.get(i).toString());
}//end for
} catch (JSONException e) {
Log.e(TAG, "onPostExecute > Try > JSONException => " + e);
e.printStackTrace();
}
adapter = new ArrayAdapter<String>(ListViewData.this, android.R.layout.simple_list_item_1, android.R.id.text1, list);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// ListView Clicked item index
int itemPosition = position;
// ListView Clicked item value
String itemValue = (String) listView.getItemAtPosition(position);
// Show Alert
Toast.makeText( ListViewData.this, "Position :" + itemPosition + " ListItem : " + itemValue, Toast.LENGTH_LONG).show();
}
});
adapter.notifyDataSetChanged();
adapter.notifyDataSetChanged();
...

we starting from conversion [ JSONArray -> List < JSONObject > ]
public static List<JSONObject> getJSONObjectListFromJSONArray(JSONArray array)
throws JSONException {
ArrayList<JSONObject> jsonObjects = new ArrayList<>();
for (int i = 0;
i < (array != null ? array.length() : 0);
jsonObjects.add(array.getJSONObject(i++))
);
return jsonObjects;
}
next create generic version replacing array.getJSONObject(i++) with POJO
example :
public <T> static List<T> getJSONObjectListFromJSONArray(Class<T> forClass, JSONArray array)
throws JSONException {
ArrayList<Tt> tObjects = new ArrayList<>();
for (int i = 0;
i < (array != null ? array.length() : 0);
tObjects.add( (T) createT(forClass, array.getJSONObject(i++)))
);
return tObjects;
}
private static T createT(Class<T> forCLass, JSONObject jObject) {
// instantiate via reflection / use constructor or whatsoever
T tObject = forClass.newInstance();
// if not using constuctor args fill up
//
// return new pojo filled object
return tObject;
}

You can use a String[] instead of an ArrayList<String>:
Hope it helps!
private String[] getStringArray(JSONArray jsonArray) throws JSONException {
if (jsonArray != null) {
String[] stringsArray = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length(); i++) {
stringsArray[i] = jsonArray.getString(i);
}
return stringsArray;
} else
return null;
}

We can simply convert the JSON into readable string, and split it using "split" method of String class.
String jsonAsString = yourJsonArray.toString();
//we need to remove the leading and the ending quotes and square brackets
jsonAsString = jsonAsString.substring(2, jsonAsString.length() -2);
//split wherever the String contains ","
String[] jsonAsStringArray = jsonAsString.split("\",\"");

To improve Pentium10s Post:
I just put the elements of the JSON array into the list with a foreach loop. This way the code is more clear.
ArrayList<String> list = new ArrayList<String>();
JSONArray jsonArray = (JSONArray)jsonObject;
jsonArray.forEach(element -> list.add(element.toString());

private String[] getStringArray(JSONArray jsonArray) throws JSONException {
if (jsonArray != null) {
String[] stringsArray = new String[jsonArray.length()];
for (int i = 0; i < jsonArray.length(); i++) {
stringsArray[i] = jsonArray.getString(i);
}
return stringsArray;
} else
return null;
}

You can use iterator:
JSONArray exportList = (JSONArray)response.get("exports");
Iterator i = exportList.iterator();
while (i.hasNext()) {
JSONObject export = (JSONObject) i.next();
String name = (String)export.get("name");
}

I know that the question was for Java. But I want to share a possible solution for Kotlin because I think it is useful.
With Kotlin you can write an extension function which converts a JSONArray into an native (Kotlin) array:
fun JSONArray.asArray(): Array<Any> {
return Array(this.length()) { this[it] }
}
Now you can call asArray() directly on a JSONArray instance.

How about using java.util.Arrays?
List<String> list = Arrays.asList((String[])jsonArray.toArray())