Java Reflection - Remove "private final" modifiers and set/get value to field

MainSandBox.java

package sandbox;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

public class MainSandBox {
	public static void main(String[] args) throws Exception {
		Example ex = new Example();
		// Change private modifier to public
		Field f = ex.getClass().getDeclaredField("id");
		f.setAccessible(true);
		// Remove final modifier
		Field modifiersField = Field.class.getDeclaredField("modifiers");
		modifiersField.setAccessible(true);
		modifiersField.setInt(f, f.getModifiers() & ~Modifier.FINAL);
		// Get and set field value
		Integer old_value = (Integer) f.get(ex);
		f.set(ex, 20);
		Integer new_value = (Integer) f.get(ex);
		// OUTPUT
		System.out.println("ex1:\n" + old_value + "\n" + new_value);
		Example ex2 = new Example();
		Field f2 = ex2.getClass().getDeclaredField("id");
		f2.setAccessible(true);
		// Get and set field value
		Integer old_value_2 = (Integer) f2.get(ex2);
		System.out.println("ex2:\n" + old_value_2);
	}
}

class Example {
	private final int	id	= 10;
}