[java] Convert normal Java Array or ArrayList to Json Array in android

Is there any way to convert a normal Java array or ArrayList to a Json Array in Android to pass the JSON object to a webservice?

ArrayList<String> list = new ArrayList<String>();
list.add("blah");
list.add("bleh");
JSONArray jsArray = new JSONArray(list);

This is only an example using a string arraylist

For a simple java String Array you should try

String arr_str [] = { "value1`", "value2", "value3" };

JSONArray arr_strJson = new JSONArray(Arrays.asList(arr_str));
System.out.println(arr_strJson.toString());

If you have an Generic ArrayList of type String like ArrayList<String>. then you should try

 ArrayList<String> obj_list = new ArrayList<>();
    obj_list.add("value1");
    obj_list.add("value2");
    obj_list.add("value3");
  JSONArray arr_strJson = new JSONArray(obj_list));
  System.out.println(arr_strJson.toString());

My code to convert array to Json

Code

List<String>a = new ArrayList<String>();
a.add("so 1");
a.add("so 2");
a.add("so 3");
JSONArray jray = new JSONArray(a);

System.out.println(jray.toString()); 

output

["so 1","so 2","so 3"]

you need external library

 json-lib-2.2.2-jdk15.jar

List mybeanList = new ArrayList();
mybeanList.add("S");
mybeanList.add("b");

JSONArray jsonA = JSONArray.fromObject(mybeanList);
System.out.println(jsonA);

Google Gson is the best library http://code.google.com/p/google-gson/

Convert ArrayList to JsonArray : Like these [{"title":"value1"}, {"title":"value2"}]

Example below :

Model class having one param title and override toString method

class Model(
    var title: String,
    var id: Int = -1
){
    
    override fun toString(): String {
        return "{\"title\":\"$title\"}"
    }
}

create List of model class and print toString

var list: ArrayList<Model>()
list.add("value1")
list.add("value2")
Log.d(TAG, list.toString())

and Here is your output

[{"title":"value1"}, {"title":"value2"}]

This is the correct syntax:

String arlist1 [] = { "value1`", "value2", "value3" };
JSONArray jsonArray1 = new JSONArray(arlist1);

example key = "Name" value = "Xavier" and the value depends on number of array you pass in

 try
      {
      JSONArray jArry=new JSONArray();
      for (int i=0;i<3;i++)
      {
       JSONObject jObjd=new JSONObject();
       jObjd.put("key", value);
       jObjd.put("key", value);
       jArry.put(jObjd);
      }
      Log.e("Test", jArry.toString());
      }
 catch(JSONException ex)
     {

     }