Jackson Create JSON Using JsonGenerator

JsonGenerator provides number of APIS to write JSON content. Following example explain, how to write simple employee information into employee.json file.

Step 1: Initialize JsonFactory.

JsonFactory factory = new JsonFactory();

Step 2: Get JsonGenerator from factory instance.

JsonGenerator generator = factory.createGenerator(new FileWriter(new File("employee.json")));

Step 3: Use write* methods of generator object for writing json data.

Step 4: Finally close generator.
generator.close();

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;

public class Main {
  public static void main(String args[]) throws IOException {
    JsonFactory factory = new JsonFactory();
    JsonGenerator generator = factory.createGenerator(new FileWriter(
        new File("employee.json")));

    /* Write JSON data */
    generator.writeStartObject();

    generator.writeFieldName("id");
    generator.writeString("1");

    generator.writeFieldName("firstName");
    generator.writeString("Hari krishna");

    generator.writeFieldName("lastName");
    generator.writeString("Gurram");

    generator.writeFieldName("hobbies");
    generator.writeStartArray();
    generator.writeString("Trekking");
    generator.writeString("Blogging");
    generator.writeString("Cooking");
    generator.writeEndArray();
    generator.writeEndObject();

    /* Close JsonGenerator */
    generator.close();

  }
}

# cat employee.json
{"id":"1","firstName":"Hari krishna","lastName":"Gurram","hobbies":["Trekking","Blogging","Cooking"]}

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