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How to get field, set and get its value by using Field class in Java Reflection API ?

Program to demonstrate working of Field class in Java Reflection API for getting field, setting and getting its value

package com.hubberspot.example;

import java.lang.reflect.Field;

class Customer {
 public String firstname;
 public String lastname;
 public String email;
 public static int counter;
}

public class FieldDemo {
 
   public static void main(String[] args) {
  
 // Create a test object. We can create
 // and apply reflection on any class 
 // we want without knowing which fields
 // it has. We are taking Customer here.
 Customer customer =  new Customer();
  
 // Getting Class associated with Customer
 Class demo = customer.getClass();
  
 try {   
  
 // Using Field class we can get field of any
 // class we want. Here we are getting field
 // firstname by calling getField method of the
 // Class associated with Customer 
  Field field = demo.getField("firstname");
   
 // After getting the field we are assigning it
 // with a value by using set method of Field
 // First parameter is the Object of Customer and
 // second parameter is the value we want to set 
  field.set(customer, "Jonty");
  
 // After assignment we are getting the value back
 // by using get method of Field and passing the 
 // Object of Customer for which we want the value 
  Object result = field.get(customer);
  
 // printing it to console
  System.out.println("Customer First Name is : "
        + result);
   
 // similarly doing for lastname and email 
  field = demo.getField("lastname");
  field.set(customer, "Magicman");
                result = field.get(customer);
  System.out.println("Customer Last Name is : "
        + result);
   
  field = demo.getField("email");
  field.set(customer, "Jonty@Magic.com");
  result = field.get(customer);
         System.out.println("Customer Email is : "
        + result);
     
  field = demo.getField("counter");
 // while working with static we are not passing
 // Object as Customer instance but we are 
 // passing it a null because its static field 
  field.set(null, 1);
  result = field.get(null);
  System.out.println("Customer Counter is : "
        + result);
  
 } catch (SecurityException e) {
   
  e.printStackTrace();
  
 } catch (NoSuchFieldException e) {
   
  e.printStackTrace();
  
 } catch (IllegalArgumentException e) {
   
  e.printStackTrace();
  
 } catch (IllegalAccessException e) {
   
  e.printStackTrace();
  
 }

   }

}




Output of the program :



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