How To Create JSON Array Using Jackson API – ObjectMapper – CreateArrayNode()

To create a JSON Object we used createObjectNode() method of ObjectMapper class. Similarly to create JSON Array we use createArrayNode() method of ObjectMapper class. createArrayNode() will return reference of ArrayNode class.

Example Json Array Object:
[

     {
	"employeeDetails" : {
			"firstname" : "Phani",
			"lastname" : "Nagula"
			}

     }
]

ObjectMapper objectMapper = new ObjectMapper();
		
// Create an array which will hold two JSON objects
ArrayNode parentArray =  objectMapper.createArrayNode();

// Creating Node that maps to JSON Object structures in JSON content
ObjectNode employeeInfo = objectMapper.createObjectNode()

employeeInfo.put("firstname", "Phani");
employeeInfo.put("lastname", "Nagula");

employeeInfo.set("employeeDetails", employeeDetails);

parentArray .add(employeeInfo);

To print created JSON array as string with proper format:

String jsonArrayAsString = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(parentArray);
System.out.println("Created Json Array is : ");
System.out.println(jsonArrayAsString);

Retrieving JSON Object from JSON array using index
// To get json array element using index
JsonNode firstElement = parentArray.get(0);
System.out.println(objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(firstElement));

Get size of JSON Array
size() method can be used to get size of JSON Array.

int sizeOfArray = parentArray.size();
System.out.println("Size of array is "+sizeOfArray);

Remove a JSON Object from JSON Array
// To remove an element from array
parentArray.remove(0);
System.out.println("After removing first element from array : "+ objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(parentArray));

Empty JSON Array
// To empty JSON Array
parentArray.removeAll();
System.out.println("After removing all elements from array : "+ objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(parentArray));