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I want to convert HashMap to json array my code is as follow:

Map<String, String> map = new HashMap<String, String>();
map.put("first", "First Value");
map.put("second", "Second Value");
I have tried this but it didn't work. Any solution?
JSONArray mJSONArray = new JSONArray(Arrays.asList(map));
                So, you have a Map, but want an Array? Well, do that conversion first, independent of JSON, and then give the result (which is now a List/Array) to the appropriate JSON converter. The code posted won't work - and will result in a compiler error, which should be included in the post - because there is no Arrays.asList(Map<K,V>), as that doesn't make sense as there is no universal conversion (although, perhaps you want a List of the Entries?). That is, this question/problem has nothing to do with JSON directly.
– user166390
                Mar 14, 2013 at 6:09
                @pst: thanks but there is any solution on it? to create array with key=> value and convert it to json? in android activity
– Sandeep
                Mar 14, 2013 at 6:12
                Arrays don't have "key=>value". Provide sample Map data and the expected JSON Array output.
– user166390
                Mar 14, 2013 at 6:13
                Key value is only available with Map family in collection,try to convert Map into String and play with String.
– subodh
                Mar 14, 2013 at 6:21
Creates a new JSONObject by copying all name/value mappings from the given map.
Parameters
copyFrom  a map whose keys are of type String and whose values are of supported types. 
Throws
NullPointerException  if any of the map's keys are null.  
Basic usage:
JSONObject obj=new JSONObject(yourmap);
get the json array from the JSONObject
Edit:
JSONArray array=new JSONArray(obj.toString());
Edit:(If found Exception then You can change as mention in comment by  @krb686)
JSONArray array=new JSONArray("["+obj.toString()+"]");
                I have no idea by what logic that is supposed to work. I can only hope it's tested - showing input and what it produces (at each stage) would make this an acceptable answer.
– user166390
                Mar 14, 2013 at 6:38
                @Pragnani Unfortunately this doesn't work.  Maybe it used to, but it doesn't anymore.  This throws:  A JSONArray text must start with '[' at character 1  At the line creating the JSONArray from the JSONObject  Fix You need to change to: JSONArray array=new JSONArray("[" + obj.toString() + "]");  Could you edit that? Thanks
– krb686
                Jun 18, 2014 at 18:50
                In java 7, api 26 android, none of the solutions above produce a valid json array output. The map.toString() function produces braces, {}, not brackets, []
– Ed J
                Jun 25, 2018 at 16:32
Since androiad API Lvl 19, you can simply do new JSONObject(new HashMap()). But on older API lvls you get ugly result(simple apply toString to each non-primitive value).
I collected methods from JSONObject and JSONArray for simplify and beautifully result. You can use my solution class:
package you.package.name;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.lang.reflect.Array;
import java.util.Collection;
import java.util.Map;
public class JsonUtils
    public static JSONObject mapToJson(Map<?, ?> data)
        JSONObject object = new JSONObject();
        for (Map.Entry<?, ?> entry : data.entrySet())
             * Deviate from the original by checking that keys are non-null and
             * of the proper type. (We still defer validating the values).
            String key = (String) entry.getKey();
            if (key == null)
                throw new NullPointerException("key == null");
                object.put(key, wrap(entry.getValue()));
            catch (JSONException e)
                e.printStackTrace();
        return object;
    public static JSONArray collectionToJson(Collection data)
        JSONArray jsonArray = new JSONArray();
        if (data != null)
            for (Object aData : data)
                jsonArray.put(wrap(aData));
        return jsonArray;
    public static JSONArray arrayToJson(Object data) throws JSONException
        if (!data.getClass().isArray())
            throw new JSONException("Not a primitive data: " + data.getClass());
        final int length = Array.getLength(data);
        JSONArray jsonArray = new JSONArray();
        for (int i = 0; i < length; ++i)
            jsonArray.put(wrap(Array.get(data, i)));
        return jsonArray;
    private static Object wrap(Object o)
        if (o == null)
            return null;
        if (o instanceof JSONArray || o instanceof JSONObject)
            return o;
            if (o instanceof Collection)
                return collectionToJson((Collection) o);
            else if (o.getClass().isArray())
                return arrayToJson(o);
            if (o instanceof Map)
                return mapToJson((Map) o);
            if (o instanceof Boolean ||
                    o instanceof Byte ||
                    o instanceof Character ||
                    o instanceof Double ||
                    o instanceof Float ||
                    o instanceof Integer ||
                    o instanceof Long ||
                    o instanceof Short ||
                    o instanceof String)
                return o;
            if (o.getClass().getPackage().getName().startsWith("java."))
                return o.toString();
        catch (Exception ignored)
        return null;
Then if you apply mapToJson() method to your Map, you can get result like this:
  "int": 1,
  "Integer": 2,
  "String": "a",
  "int[]": [1,2,3],
  "Integer[]": [4, 5, 6],
  "String[]": ["a","b","c"],
  "Collection": [1,2,"a"],
  "Map": {
    "b": "B",
    "c": "C",
    "a": "A"
                Sweet!  I wish I could give this +10!  I'll have to look at the source code for API 19 to see if this is what they're doing.  Thanks!
– bstar55
                Jun 20, 2014 at 21:51
                Had the same problem with undecodable string being sent looking like:  {key=value, key2=value2}
– Vans S
                Jul 6, 2016 at 23:14
A map consists of key / value pairs, i.e. two objects for each entry, whereas a list only has a single object for each entry. What you can do is to extract all Map.Entry<K,V> and then put them in the array:
Set<Map.Entry<String, String> entries = map.entrySet();
JSONArray mJSONArray = new JSONArray(entries);
Alternatively, sometimes it is useful to extract the keys or the values to a collection:
Set<String> keys = map.keySet();
JSONArray mJSONArray = new JSONArray(keys);
List<String> values = map.values();
JSONArray mJSONArray = new JSONArray(values);
Note: If you choose to use the keys as entries, the order is not guaranteed (the keySet() method returns a Set). That is because the Map interface does not specify any order (unless the Map happens to be a SortedMap). 
                These classes are available in JSON-Lib library. You can find this library here: json-lib.sourceforge.net
– Sadeshkumar Periyasamy
                Mar 14, 2013 at 6:15
                @Forhad: Thanks, But my hash created dynamically in my code so its not suitable for me is any other option to create array with key=>value and convert in json in android activity?
– Sandeep
                Mar 14, 2013 at 6:16
        
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