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How to Write/create a JSON array using Java?
A JSON array is an ordered collection of values that are enclosed in square brackets i.e., it begins with '[' and ends with ']'. The values in the arrays are separated by ',' (comma).
Sample JSON array
{
"books": [ Java, JavaFX, Hbase, Cassandra, WebGL, JOGL]
}The JSON-simple is a light weight library which is used to process JSON objects. Using this you can read or, write the contents of a JSON document using Java program.
JSON-Simple maven dependency
Following is the maven dependency for the JSON-simple library −
<dependencies> <dependency> <groupId>com.googlecode.json-simple</groupId> <artifactId>json-simple</artifactId> <version>1.1.1</version> </dependency> </dependencies>
Paste this with in the <dependencies> </dependencies> tag at the end of your pom.xml file. (before </project> tag)
Example
To create an array in a JSON file using a Java program −
- Instantiate the JSONObject class of the json-simple library.
//Creating a JSONObject object JSONObject jsonObject = new JSONObject();
- Insert the required key-value pairs using the put() method of the JSONObject class.
jsonObject.put("key", "value");- Create a JSON array by instantiating the JSONArray class and add, elements to the created array using the add() method of the JSONArray class.
JSONArray array = new JSONArray();
array.add("element_1");
array.add("element_2");
array.add("element_3");- After adding all the required elements add the array into the JSON document using the put() method as −
jsonObject.put("contact",array);- Write the created JSON object into a file using the FileWriter class as −
FileWriter file = new FileWriter("E:/json_array_output.json");
file.write(jsonObject.toJSONString());
file.close();Following Java program creates a JSON object with an array in it and writes it into a file named json_array_output.json.
Example
import java.io.FileWriter; import java.io.IOException; import org.json.simple.JSONArray; import org.json.simple.JSONObject; public class WritingJSONArray { public static void main(String args[]) { //Creating a JSONObject object JSONObject jsonObject = new JSONObject(); //Inserting key-value pairs into the json object jsonObject.put("ID", "1"); jsonObject.put("First_Name", "Krishna Kasyap"); jsonObject.put("Last_Name", "Bhagavatula"); jsonObject.put("Date_Of_Birth", "1989-09-26"); jsonObject.put("Place_Of_Birth", "Vishakhapatnam"); jsonObject.put("Country", "25000"); //Creating a json array JSONArray array = new JSONArray(); array.add("e-mail: krishna_kasyap@gmail.com"); array.add("phone: 9848022338"); array.add("city: Hyderabad"); array.add("Area: Madapur"); array.add("State: Telangana"); //Adding array to the json object jsonObject.put("contact",array); try { FileWriter file = new FileWriter("E:/json_array_output.json"); file.write(jsonObject.toJSONString()); file.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println("JSON file created: "+jsonObject); } }
Output
JSON file created: {
"First_Name":"Krishna Kasyap",
"Place_Of_Birth":"Vishakhapatnam",
"Last_Name":"Bhagavatula",
"contact":[
"e-mail: krishna_kasyap@gmail.com",
"phone: 9848022338","city: Hyderabad",
"Area: Madapur",
"State: Telangana"],
"Country":"25000",
"ID":"1",
"Date_Of_Birth":"1989-09-26"}If you observe the contents of the JSON file you can see the created data as −
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