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spring-loaded rocks !

Today I found spring loaded (
in short this is a java agent that enables class reloading of already running VM.
Simply this means zero deployment time (in many cases).
It is like a free and open source alternative of JRebel.
Spring Loaded allows you to add/modify/delete methods/fields/constructors. The annotations on types/methods/fields/constructors can also be modified and it is possible to add/remove/change values in enum types.
There is a preliminary java8 support. There is also another project DCEVM ( which is also great but supports only till JRE 6 update 26). More info here
But lets stop speaking and show you how it works.
In short you just need to pass the agent when starting the vm and that’s it.
>java -javaagent:D:/Downloads/springloaded-1.2.0.BUILD-20140409.201438-12.jar -noverify org.gochev.MainClass
I am using this Build since I am running Java 8 and this is currently the latest .
The code I in my simple app is the following:
A POJO like this :
package org.gochev;

public class DynamicReloadedClass {
 private int age = 30;

 public int getAge() {
  return age;

 public void setAge(int age) {
  this.age = age;

and a MainClass like this:

package org.gochev;

import java.util.Scanner;

public class MainClass {
 public static void main(String[] args) {
  try (Scanner scanner = new Scanner( {
   while (true) {
    System.out.println("test "
    + new DynamicReloadedClass().getAge());;

So I can change the DynamicReloadedClass while the main method in the MainClass is looping. You can see this in action here :

Awesome ... and free ! 


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