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));
}
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));
Java Guides
javaguides.net › 2019 › 07 › convert-list-to-json-array-using-jackson.html
Convert List to JSON Array Using Jackson
July 21, 2019 - package net.javaguides.jackson; import java.util.ArrayList; import java.util.List; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.SerializationFeature; /** * Using Jackson API for list serialization and deserialization * @author ramesh fadatare * */ public class JacksonListToJson { public static void main(String[] args) throws JsonProcessingException { // Create ObjectMapper object.
TutorialsPoint
tutorialspoint.com › article › how-to-convert-a-list-to-json-array-using-the-jackson-library-in-java
How to convert a List to JSON array using the Jackson library in Java?
April 29, 2025 - import java.util.*; import com.fasterxml.jackson.databind.*; import com.fasterxml.jackson.databind.node.ArrayNode; public class ListToJSONArrayUsingArrayNode { public static void main(String[] args) { List < String > list = Arrays.asList("JAVA", "PYTHON", "SCALA", ".NET", "TESTING"); ObjectMapper objectMapper = new ObjectMapper(); ArrayNode arrayNode = objectMapper.createArrayNode(); for (String item: list) { arrayNode.add(item); // adding each item manually } try { String jsonArray = objectMapper.writeValueAsString(arrayNode); System.out.println(jsonArray); } catch (Exception e) { e.printStackTrace(); } } }
How to do in Java
howtodoinjava.com › home › convert json array to list in java: jackson, gson, org.json
Convert JSON Array to List in Java: Jackson, Gson, Org.json
3 weeks ago - JsonMapper mapper = JsonMapper... JSONArray(json).toList() returns the strings as a List<Object>. Call writeValueAsString(list) on the Jackson mapper or toJson(list) on Gson....
CodingTechRoom
codingtechroom.com › question › efficiently-write-java-list-json-array-jackson
How to Efficiently Write a Java List as a JSON Array using Jackson - CodingTechRoom
Copied · ArrayList<Event> list ...ValueAsString(list); Using Jackson to convert a Java ArrayList into a JSON array can be done efficiently with the `ObjectMapper` class....
Stack Abuse
stackabuse.com › converting-json-array-to-a-java-array-or-list
Convert JSON Array to a Java Array or List with Jackson
September 8, 2020 - Using Jackson's ObjectMapper class, it's easy to read values and map them to an object, or an array of objects. We just use the readValue() method, passing the JSON contents and the class we'd like to map to.
Apps Developer Blog
appsdeveloperblog.com › home › java › java json › convert json array to java list using jackson
Convert JSON Array to Java List using Jackson - Apps Developer Blog
March 22, 2024 - import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import java.util.ArrayList; import java.util.List; public class ManualConversionExample { public static void main(String[] args) { String jsonArrayString = "[{\"id\": 1, \"name\": \"John\"}, {\"id\": 2, \"name\": \"Jane\"}]"; ObjectMapper objectMapper = new ObjectMapper(); try { JsonNode jsonArray = objectMapper.readTree(jsonArrayString); List<Person> personList = new ArrayList<>(); for (JsonNode element : jsonArray) { Person person = objectMapper.treeToValue(element, Person.class); personList.a
TutorialsPoint
tutorialspoint.com › article › how-can-we-convert-a-json-array-to-a-list-using-jackson-in-java
How can we convert a JSON array to a list using Jackson in Java?
June 5, 2025 - Jackson is a Java-based library, and it can be useful for converting Java objects to JSON and JSON to Java objects. A Jackson API is faster than other API, needs less memory, and is good for large objects.
Mkyong
mkyong.com › home › java › how to parse json array with jackson
How to parse JSON Array with Jackson | mkyong.com
April 23, 2024 - package com.mkyong.json.jackson; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; import com.mkyong.json.model.Person; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; public class JsonArrayToObjectExample3 { public static void main(String[] args) throws JsonProcessingException { // Create a list of Person objects List<Person> people = Arrays.asList( new Person("mkyong", 42), new Person("ah pig", 20) ); // Wrap the list in a Map with "Person" as the key Map<String, List<Person>> wrapper
Top answer 1 of 5
98
The problem is not in your code but in your json:
{"Compemployes":[{"id":1001,"name":"jhon"}, {"id":1002,"name":"jhon"}]}
this represents an object which contains a property Compemployes which is a list of Employee. In that case you should create that object like:
class EmployeList{
private List<Employe> compemployes;
(with getter an setter)
}
and to deserialize the json simply do:
EmployeList employeList = mapper.readValue(jsonString,EmployeList.class);
If your json should directly represent a list of employees it should look like:
[{"id":1001,"name":"jhon"}, {"id":1002,"name":"jhon"}]
Last remark:
List<Employee> list2 = mapper.readValue(jsonString,
TypeFactory.collectionType(List.class, Employee.class));
TypeFactory.collectionType is deprecated you should now use something like:
List<Employee> list = mapper.readValue(jsonString,
TypeFactory.defaultInstance().constructCollectionType(List.class,
Employee.class));
2 of 5
1
/*
It has been answered in http://stackoverflow.com/questions/15609306/convert-string-to-json-array/33292260#33292260
* put string into file jsonFileArr.json
* [{"username":"Hello","email":"hello@email.com","credits"
* :"100","twitter_username":""},
* {"username":"Goodbye","email":"goodbye@email.com"
* ,"credits":"0","twitter_username":""},
* {"username":"mlsilva","email":"mlsilva@email.com"
* ,"credits":"524","twitter_username":""},
* {"username":"fsouza","email":"fsouza@email.com"
* ,"credits":"1052","twitter_username":""}]
*/
public class TestaGsonLista {
public static void main(String[] args) {
Gson gson = new Gson();
try {
BufferedReader br = new BufferedReader(new FileReader(
"C:\\Temp\\jsonFileArr.json"));
JsonArray jsonArray = new JsonParser().parse(br).getAsJsonArray();
for (int i = 0; i < jsonArray.size(); i++) {
JsonElement str = jsonArray.get(i);
Usuario obj = gson.fromJson(str, Usuario.class);
//use the add method from the list and returns it.
System.out.println(obj);
System.out.println(str);
System.out.println("-------");
}
} catch (IOException e) {
e.printStackTrace();
}
}
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 - package org.example; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; import java.util.ArrayList; import java.util.List; public class Main { public static void main(String[] args) { // Create an ArrayList of objects List<Course> courses = new ArrayList<>(); courses.add( new Course(1, "Java", "25000", "3 Months")); courses.add( new Course(2, "C++", "20000", "3 Months")); // Convert the ArrayList to a JSON array ObjectMapper objectMapper = new ObjectMapper(); try { String jsonArray = objectMapper.writeValueAsString(courses); System.out.println(jsonArray); } catch (JsonProcessingException e) { e.printStackTrace(); } } }
Baeldung
baeldung.com › home › json › jackson › convert json array to java list
Convert JSON Array to Java List | Baeldung
August 13, 2025 - In this tutorial, we’ll compare different approaches to achieving this conversion using two popular JSON libraries in Java – Gson and Jackson.
Baeldung
baeldung.com › home › json › jackson › jackson – unmarshall to collection/array
Jackson - Unmarshall to Collection/Array | Baeldung
April 26, 2024 - If you want to dig deeper and learn other cool things you can do with the Jackson 2 – head on over to the main Jackson tutorial. ... @Test public void givenJsonArray_whenDeserializingAsArray_thenCorrect() throws JsonParseException, JsonMappingException, IOException { ObjectMapper mapper = new ObjectMapper(); List<MyDto> listOfDtos = Lists.newArrayList( new MyDto("a", 1, true), new MyDto("bc", 3, false)); String jsonArray = mapper.writeValueAsString(listOfDtos); // [{"stringValue":"a","intValue":1,"booleanValue":true}, // {"stringValue":"bc","intValue":3,"booleanValue":false}] MyDto[] asArray = mapper.readValue(jsonArray, MyDto[].class); assertThat(asArray[0], instanceOf(MyDto.class)); }
Level Up Lunch
leveluplunch.com › java › examples › convert-json-array-to-arraylist-of-objects-jackson
Json array to ArrayList jackson | Level Up Lunch
April 5, 2014 - First we will create an ObjectMapper, a class that provides the ability to convert between java and json, to deserialize json to java ArrayList.
YouTube
youtube.com › phcodegyan videos
Parse JSON to Java Object,ArrayList & Array Using Jackson Library - YouTube
This video shows how to parse json into Java Object,ArrayList and Array.Jackson Library has been used to achieve the same.At 0:37 secs , it's Maven based jav...
Published: July 31, 2021
Views: 22K
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\": \"ravi@gmail.com\",\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\": \"johnny_depp@gmail.com\",\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\": \"leonardo_dicaprio@gmail.com\",\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\": \"john_wayne@gmail.com\",\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\": \"angelina_jolie@gmail.com\",\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\": \"dido@gmail.com\",\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\": \"adele@gmail.com\",\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\": \"hugh_jackman@gmail.com\",\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\": \"will_smith@gmail.com\",\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\": \"clint_eastwood@gmail.com\",\n" +
" \"address\": \"xx-xx-xxxx,x - street, x - country\",\n" +
" \"gender\" : \"male\",\n" +
" \"phone\": {\n" +
" \"mobile\": \"+91 0000000000\",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 - After adding the required dependency, we’ll use the ObjectMapper class from Jackson to convert the Java List to a JSON array as follows: @Test public void given_JavaList_whenUsingJacksonLibrary_thenOutJsonArray() throws JsonProcessingException ...
Top answer 1 of 4
19
To convert ArrayList to Json, just download Open Source json utility from: http://json.org/java/ or Jar file from here
And just do:
JSONArray jsonAraay = new JSONArray(your_array_list);
That's it
Note: You should have setter/getter in your POJO/MODEL class to convert arraylist to json
2 of 4
1
Don't bother with org.json, use Jackson all the way:
// list is a List<MyData>
final ObjectMapper mapper = new ObjectMapper();
final Map<String, MyData> map = new HashMap<>();
for (final MyData data: list)
map.put(data.fname, data);
final JsonNode json = mapper.valueToTree(map);
Attacomsian
attacomsian.com › blog › jackson-convert-json-array-to-from-java-list
Convert JSON array to a list using Jackson in Java
November 6, 2022 - In this short tutorial, you’ll learn how to use the Jackson library to convert a JSON array string into a list of Java Objects and vice versa.
YouTube
youtube.com › watch
Java json 01 create an arraylist to serialize with Jackson library - YouTube
Shows how to prepare an arraylist of a class. Preparing for use of a json library called Jackson. Part 1 of 3 for how to read and write json files using java
Published: January 29, 2019