If I read the JSONArray constructors correctly, you can build them from any Collection (arrayList is a subclass of Collection) like so:
ArrayList<String> list = new ArrayList<String>();
list.add("foo");
list.add("baar");
JSONArray jsArray = new JSONArray(list);
References:
- jsonarray constructor: http://developer.android.com/reference/org/json/JSONArray.html#JSONArray%28java.util.Collection%29
- collection: http://developer.android.com/reference/java/util/Collection.html
Top answer 1 of 9
138
If I read the JSONArray constructors correctly, you can build them from any Collection (arrayList is a subclass of Collection) like so:
ArrayList<String> list = new ArrayList<String>();
list.add("foo");
list.add("baar");
JSONArray jsArray = new JSONArray(list);
References:
- jsonarray constructor: http://developer.android.com/reference/org/json/JSONArray.html#JSONArray%28java.util.Collection%29
- collection: http://developer.android.com/reference/java/util/Collection.html
2 of 9
77
Use Gson library to convert ArrayList to JsonArray.
Gson gson = new GsonBuilder().create();
JsonArray myCustomArray = gson.toJsonTree(myCustomList).getAsJsonArray();
Baeldung
baeldung.com › home › java › java list › converting a java list to a json array
Converting a Java List to a Json Array | Baeldung
June 18, 2025 - @Test public void given_JavaList_whenUsingGsonLibrary_thenOutJsonArray() { Gson gson = new Gson(); String jsonArray = gson.toJson(list); Assert.assertEquals(expectedJsonArray, jsonArray); }
Videos
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TutorialsPoint
tutorialspoint.com › how-to-convert-java-array-or-arraylist-to-jsonarray-using-gson-in-java
How to convert Java array or ArrayList to JsonArray using Gson in Java?
import com.google.gson.*; import java.util.*; public class JavaArrayToJsonArrayTest { public static void main(String args[]) { String[][] strArray = {{"elem1-1", "elem1-2"}, {"elem2-1", "elem2-2"}}; ArrayList<ArrayList<String>> arrayList = new ArrayList<>(); for(int i = 0; i < strArray.length; i++) { ArrayList<String> nextElement = new ArrayList<>(); for(int j = 0; j < strArray[i].length; j++) { nextElement.add(strArray[i][j] + "-B"); } arrayList.add(nextElement); } JsonObject jsonObj = new JsonObject(); // array to JsonArray JsonArray jsonArray1 = new Gson().toJsonTree(strArray).getAsJsonArray(); // ArrayList to JsonArray JsonArray jsonArray2 = new Gson().toJsonTree(arrayList).getAsJsonArray(); jsonObj.add("jsonArray1", jsonArray1); jsonObj.add("jsonArray2", jsonArray2); System.out.println(jsonObj.toString()); } }
Top answer 1 of 16
204
ArrayList<String> listdata = new ArrayList<String>();
JSONArray jArray = (JSONArray)jsonObject;
if (jArray != null) {
for (int i=0;i<jArray.length();i++){
listdata.add(jArray.getString(i));
}
}
2 of 16
85
I've done it using Gson (by Google).
Add the following line to your module's build.gradle:
dependencies {
// ...
// Note that `compile` will be deprecated. Use `implementation` instead.
// See https://stackoverflow.com/a/44409111 for more info
implementation 'com.google.code.gson:gson:2.8.2'
}
JSON string:
private String jsonString = "[\n" +
" {\n" +
" \"id\": \"c200\",\n" +
" \"name\": \"Ravi Tamada\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c201\",\n" +
" \"name\": \"Johnny Depp\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c202\",\n" +
" \"name\": \"Leonardo Dicaprio\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c203\",\n" +
" \"name\": \"John Wayne\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c204\",\n" +
" \"name\": \"Angelina Jolie\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"female\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c205\",\n" +
" \"name\": \"Dido\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"female\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c206\",\n" +
" \"name\": \"Adele\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"female\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c207\",\n" +
" \"name\": \"Hugh Jackman\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c208\",\n" +
" \"name\": \"Will Smith\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c209\",\n" +
" \"name\": \"Clint Eastwood\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c2010\",\n" +
" \"name\": \"Barack Obama\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c2011\",\n" +
" \"name\": \"Kate Winslet\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"female\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" },\n" +
" {\n" +
" \"id\": \"c2012\",\n" +
" \"name\": \"Eminem\",\n" +
" \"email\": \"[email protected]\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",\n" +
" \"home\": \"00 000000\",\n" +
" \"office\": \"00 000000\"\n" +
" }\n" +
" }\n" +
" ]";
ContactModel.java:
public class ContactModel {
public String id;
public String name;
public String email;
}
Code for converting a JSON string to ArrayList<Model>:
Note: You have to import java.lang.reflect.Type;:
// Top of file
import java.lang.reflect.Type;
// ...
private void parseJSON() {
Gson gson = new Gson();
Type type = new TypeToken<List<ContactModel>>(){}.getType();
List<ContactModel> contactList = gson.fromJson(jsonString, type);
for (ContactModel contact : contactList){
Log.i("Contact Details", contact.id + "-" + contact.name + "-" + contact.email);
}
}
Hope this will help you.
GeeksforGeeks
geeksforgeeks.org › java › how-to-convert-an-arraylist-of-objects-to-a-json-array-in-java
How to Convert an ArrayList of Objects to a JSON Array in Java? - GeeksforGeeks
July 23, 2025 - In the above code, a Java class called Course models the properties of a course like its id, name, fees, and duration. It has getter and setter methods to access and modify the private fields. Here we are adding the logic of converting an ArrayList of objects to a JSON array of Java in the main class.
TutorialsPoint
tutorialspoint.com › how-can-we-convert-a-list-to-the-json-array-in-java
How can we convert a list to the JSON array in Java?
April 22, 2025 - import java.util.Arrays; import java.util.List; public class ManualJsonArray { public static void main(String[] args) { List<String> list = Arrays.asList("apple", "banana", "cherry"); StringBuilder jsonArray = new StringBuilder("["); for (int i = 0; i < list.size(); i++) { jsonArray.append(""").append(list.get(i)).append("""); if (i < list.size() - 1) jsonArray.append(", "); } jsonArray.append("]"); System.out.println("JSON Array: " + jsonArray.toString()); } }
Top answer 1 of 8
117
If you want or need to work with a Java array then you can always use the java.util.Arrays utility classes' static asList() method to convert your array to a List.
Something along those lines should work.
String mStringArray[] = { "String1", "String2" };
JSONArray mJSONArray = new JSONArray(Arrays.asList(mStringArray));
Beware that code is written offhand so consider it pseudo-code.
2 of 8
40
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
Crunchify
crunchify.com › json tutorials › in java how to convert arraylist to jsonobject?
In Java How to Convert ArrayList to JSONObject? • Crunchify
May 17, 2018 - package crunchify.com.tutorial; import java.util.ArrayList; import com.google.gson.Gson; import com.google.gson.GsonBuilder; /** * @author Crunchify.com * Program: Best way to convert Java ArrayList to JSONObject * Version: 1.0.0 * */ public class CrunchifyArrayListToJsonObject { public static void main(String a[]) { ArrayList<String> crunchify = new ArrayList<String>(); crunchify.add("Google"); crunchify.add("Facebook"); crunchify.add("Crunchify"); crunchify.add("Twitter"); crunchify.add("Snapchat"); crunchify.add("Microsoft"); log("Raw ArrayList ===> " + crunchify); // Use this builder to construct a Gson instance when you need to set configuration options other than the default.
Baeldung
baeldung.com › home › json › jackson › convert json array to java list
Convert JSON Array to Java List | Baeldung
August 13, 2025 - Learn how to convert a JSON array to a Java List using the popular Gson and Jackson libraries.
GitHub
gist.github.com › 21ec4a3a1fe9dc52e2cd195479428f98
JAVA array or ArrayList to JsonArray (Gson) · GitHub
JAVA array or ArrayList to JsonArray (Gson). GitHub Gist: instantly share code, notes, and snippets.
YouTube
youtube.com › watch
Java JSON Array Encode Using ArrayList - YouTube
#JavaJSONArray #HomeStay #StaySafe #ArrayList #JSONArrayListJava JSON ArrayList Encode0:05 JSON Install1:53 JSON Array Example Start time:Like, Share, And Su...
Published April 7, 2020
Coderanch
coderanch.com › t › 713115 › java › conversion-array-list-Json-object
conversion of array list to Json object string (Java in General forum at Coderanch)
July 19, 2019 - programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums · this forum made possible by our volunteer staff, including ... ... Hi I have two lists Edge1List and Edge2List which I add to element on them. Edge1List:[o,p] and Edge2List: [p,null]. I convert Edge1List and Edge2List to JsonArray with the name of EdgeJsonArray1 and EdgeJsonArray2 respectively.
BeginnersBook -
beginnersbook.com › home › java › convert json array to arraylist in java
Convert JSON Array to ArrayList in Java
June 13, 2024 - 2. Parse the JSON Array and Convert ... \"age\":37}, {\"name\":\"Rahul\", \"age\":34}]"; // Convert JSON array to JSONArray JSONArray jsonArray = new JSONArray(jsonArrayString); // Convert JSONArray to ArrayList ArrayList<JSONObject> arrayList = new ArrayList<>(); for (int ...
Top answer 1 of 5
3
If you want to work with json go this library, this library has a nice support https://code.google.com/p/google-gson/.
This is an example:
Gson gson = new Gson();
Collection<Integer> ints = Lists.immutableList(1,2,3,4,5);
(Serialization)
String json = gson.toJson(ints); ==> json is [1,2,3,4,5]
Thanks
2 of 5
3
org.json and org.json.simple JSON parser use raw types of collections underneath. If you're looking for good Generics support try Google Gson. Here's how you would go about serializing your generic ArrayList with Gson:
Gson gson = new Gson();
ArrayList<String> arrayList= (ArrayList<String>) ClassName.getArrayList();
// Serializing to a JSON element node
JsonElement jsonElement = gson.toJsonTree(arrayList);
System.out.println(jsonElement.isJsonArray()); // true
// Or, directly to JSON string
String json = gson.toJson(arrayList);
System.out.println(json);
Here's how you would deserialize the same JSON string with its Generics intact:
Type type = new TypeToken<ArrayList<String>>(){}.getType();
ArrayList<String> arrayList = gson.fromJson(json, type);
Top answer 1 of 9
23
Using Gson Library it will be very simple.
From JSON String to ArrayList of Object as:
Type listType =
new TypeToken<ArrayList<Student>>(){}.getType();
ArrayList<Student> yourClassList = new Gson().fromJson(jsonArray, listType);
And to Json from Array List of Object as:
ArrayList<Student> sampleList = new ArrayList<Student>();
String json = new Gson().toJson(sampleList);
The Gson Library is more simple to use than JSONObject and JSONArray implementation.
2 of 9
21
You will have to include the jettison jar in you project and import the required classes.
JSONObject jObject = new JSONObject();
try
{
JSONArray jArray = new JSONArray();
for (Student student : sudentList)
{
JSONObject studentJSON = new JSONObject();
studentJSON.put("name", student.getName());
studentJSON.put("age", student.getAge());
jArray.put(studentJSON);
}
jObject.put("StudentList", jArray);
} catch (JSONException jse) {
jse.printStacktrace();
}
GeeksforGeeks
geeksforgeeks.org › java › convert-an-arraylist-into-a-json-string-in-java
How to Convert an ArrayList into a JSON String in Java? - GeeksforGeeks
July 23, 2025 - It uses the ObjectMapper from Jackson to convert the ArrayList to a JSON string.
GitHub
gist.github.com › sheharyarn › cba56ff154de2cc62fc5
Simple Java Class to convert Lists/Maps to JSON and vice versa · GitHub
Simple Java Class to convert Lists/Maps to JSON and vice versa - SimpleJSON.java
Google Groups
groups.google.com › g › vertx › c › 5fgz-e2rTbk
casting a JsonArray to a specific type
Also, if you're using Java 8 you can make the List to List<String> conversion a little prettier with the stream API. Something like... List<String> list = array.toList().stream().collect(Collectors.mapping(value -> value.toString()), Collectors::toList); Might have that a little wrong since I typed that from my phone :-) On Dec 28, 2014, at 3:23 PM, Alexander Lehmann <alex...@gmail.com> wrote: I wonder if there is a smarter way to cast a JsonArray to a List of specific type.
Top answer 1 of 4
68
This is overly complicated, Jackson handles lists via its writer methods just as well as it handles regular objects. This should work just fine for you, assuming I have not misunderstood your question:
public void writeListToJsonArray() throws IOException {
final List<Event> list = new ArrayList<Event>(2);
list.add(new Event("a1","a2"));
list.add(new Event("b1","b2"));
final ByteArrayOutputStream out = new ByteArrayOutputStream();
final ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(out, list);
final byte[] data = out.toByteArray();
System.out.println(new String(data));
}
2 of 4
29
I can't find toByteArray() as @atrioom said, so I use StringWriter, please try:
public void writeListToJsonArray() throws IOException {
//your list
final List<Event> list = new ArrayList<Event>(2);
list.add(new Event("a1","a2"));
list.add(new Event("b1","b2"));
final StringWriter sw =new StringWriter();
final ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(sw, list);
System.out.println(sw.toString());//use toString() to convert to JSON
sw.close();
}
Or just use ObjectMapper#writeValueAsString:
final ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(list));