import java.io.IOException; 
import com.fasterxml.jackson.databind.ObjectMapper; 

public class JacksonTester {
   public static void main(String args[]){
      ObjectMapper mapper = new ObjectMapper();
      try {
         Student student = new Student("Mark", 1);
         String jsonString = mapper 
            .writerWithDefaultPrettyPrinter()
            .writeValueAsString(student);
         System.out.println(jsonString);
      }
      catch (IOException e) {
         e.printStackTrace();
      }
   }
}
class Student {
   private String name;
   private int rollNo;
   public Student(String name, int rollNo){
      this.name = name;
      this.rollNo = rollNo;
   }  
   public String getStudentName(){
      return name;
   } 
   public int getRollNo(){
      return rollNo;
   }
}

{
   "studentName" : "Mark",
   "rollNo" : 1
} 

import java.io.IOException;
import com.fasterxml.jackson.databind.ObjectMapper; 
import com.fasterxml.jackson.annotation.JsonGetter; 

public class JacksonTester {
   public static void main(String args[]){ 
      ObjectMapper mapper = new ObjectMapper(); 
      try {
         Student student = new Student("Mark", 1);    
         String jsonString = mapper 
            .writerWithDefaultPrettyPrinter() 
            .writeValueAsString(student); 
         System.out.println(jsonString); 
      } 
      catch (IOException e) { 
         e.printStackTrace();  
      }   
   }
}
class Student {
   private String name;
   private int rollNo;
   public Student(String name, int rollNo){
      this.name = name;
      this.rollNo = rollNo;
   }
   @JsonGetter
   public String getStudentName(){
      return name;
   }
   public int getRollNo(){
      return rollNo;
   }
}

{
   "name" : "Mark",
   "rollNo" : 1
}