0

spring-loaded rocks !

Posted by JOKe on 4/22/2014 09:37:00 PM

Today I found spring loaded (https://github.com/spring-projects/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 http://ssw.jku.at/dcevm/

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(System.in)) {
while (true) {
System.out.println("test "
+ new DynamicReloadedClass().getAge());
scanner.next();
}
}
}
}


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



http://www.screencast.com/t/KIFIxv7j



Awesome ... and free ! 


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0

Google Reader alternatives ?

Posted by JOKe on 6/26/2013 01:52:00 PM

None .. no really there is NO Google reader alternatives simply because Google reader is THE BEST.

However since google reader will be shut down in few days and we don’t have a choice and we have to switch somewhere. So what are the alternatives one day before the google shutdown ?

1) Feedly : http://cloud.feedly.com/#latest

I hate it .. no really it is HELL of a BUGGY .. it doesn’t mark my blog posts as read.. it requires some crappy plugins that will fetch the articles in the background otherwise it is not working, the android app is peace of buggy shit with some promotional popular craps and no real full article view for tablets. It is amazingly bad.. it looks shiny but it is shit, it requires login on all your machines each time when you make changes between the machine (work, home, phone). It is unusable even when it looks good :

feedly

It looks good but it is not an alternative.. no my friends its peace of crap that just wants to steal some google reader users.

2) AOL reader : http://reader.aol.com/ currently in  closed beta.

It is not bad actually it looks good it works good (when it works) however it is not working like 30% of the time still it may become a good alternative ones it is done but it wont be done tomorrow so .. nope it doesn’t work for me.

It looks like that :

 

3) Digg Reader : http://digg.com/reader currently in closed beta.

Good idea however it is hell of a buggy doesn’t looks and works very well and maybe some day it will be okei as AOL reader but this day is not today.

It looks like that:

4) NewsBlur, Pulse, Flipboard, NetVibes, Zite are basicaly RSS readers but not a Google reader alternatives.

You can read about all of them here http://gizmodo.com/10-google-reader-alternatives-that-will-ease-your-rss-p-5990540 however I don’t like them at all they look bad and they are useless for a lot of news. Sometimes I have 1500 news per day that I want to scroll as fast as possible and read only the 50 of them which are really liked so this readers to me and I guess for many of you as well cuz this readers simply doesn’t do the job.

So what can we do ? what is left ? yes what is left is the REAL alternative. The real alternative is called

5) Old Reader : http://theoldreader.com/ works and looks like a boss !

First of all no complains about how it works, it marks everything right on time I don’t have to cilck some crappy button “Mark all my articles as read” like in feebly otherwise 50% of your already checked articles are unread … also Feedly doesn’t show you all unreaded articles it is peace of shit anyway Old Reader is awesome and it is not just created a month ago by 3 random php guys who are trying to type something that can read XML file and show html instead it is old product which already have users, which is already stable and proven and it doesn’t require some weird browser extensions. The social plugins are missing indeed share on facebook or on google+ however there are bookmarklets for this I was always wonder before how you can share something before you actually read it just watching the headlines ? it is just strange… Anyway by default the reader looks like this (after last UI changes that the old reader team made) :

I know what you will say : it looks bad.. Indeed I don’t like how it looks as well.. what I did in order to LOVE this reader is well I installed Stylish extension ( I already had it ). Stylish extension gives you a way to apply any css to any website that you visit.. for example you have something in Facebook you don’t wanna see then add a selector and hide it..  so for the old reader there are tons of css styles reader UI is made very nicely and all the css classes are nicely called everything is very easy for customization here is my try if someone want to use it : https://skydrive.live.com/redir.aspx?cid=3917982854a57d45&page=self&resid=3917982854A57D45!176&parid=3917982854A57D45!102&authkey=!&Bpub=SDX.SkyDrive&Bsrc=Share 

Just add this style in Stylish add the URL starting with http://theoldreader.com/ and voala:

oldreader

 

Well that’s it guys – THE OLD READER the ONLY Google reader alternative on 26.06.2013.


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0

Семинар: Новости в Java платформата.

Posted by JOKe on 7/21/2011 05:12:00 PM

 

Анонса е леко нахално взаимстван от блога на Наков(http://www.nakov.com/blog/2011/07/21/seminar-java-7-java-ee-6-bgjug-27-july-2011/) поради мързел от моя страна да го напиша. Общо взето промените са replace на Найден Гочев с Аз.

 

Имам прекрасна новина за всички Java фенове. След като Java 7 официално излезе, дойде ред и на Българскота общност от Java разработчици да се присъедини към поредицата “Java 7 Launch” събития. Благодарение на много хора :+) ще си направим семинарче и парти по случай Java 7 и новостите от Java света, които идват заедно с нея.

Програма на семинара

    Kакво ново в Java 7?
    Kакво ново в Java EE 6?
    Kакво ново в JavaFX 2.0?
    Kакво ново в JavaME?

Лекциите са част от официалния “Oracle Java 7 Launch Kit”, който е предоставен от Oracle за Българската Java потребителска група (BGJUG) заедно с тениски и други рекламни материали.

Кога и къде?

Семинарът “Новости от Java платформата” ще се проведе на 27 юли (сряда) от 19:00 часа в учебната зала на Академията на Телерик за софтуерни инженери. Адресът е: София, Младост-1, бул. Александър Малинов 33, партер.

Лектор

Лектор ще бъда аз.

Благодарности

Благодарностите за организирането на семинара са за:

    BGJUG – организатор на събитието
    Oracle Corp. които предоставиха Java 7 Launch Kit, тениски и рекламни материали за BGJUG
    Петър Тахчиев, който поръча тениските и launch kit-a.   
    Академия на Телерик – домакин на събитието
    Светлин Наков, който помогна с намирането на домакин ;)



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0

JavaScript inheritance (object-oriented programming)

Posted by JOKe on 7/05/2011 04:47:00 PM in

 

There are many posts explaining what JavaScript inheritance is how it works, is it bad or good, how it is comparable with Java inheritance with millions of examples using third party apis or function to make inheritance look more like C#/C++/Java Inheritance.

This post is just to show HOW inheritance looks without anything else except browser so next time when you need to find it you can open this post which explains everything you need.

JavaScript uses so called prototype inheritance you don’t need to know more except it is different then a C#/C++/Java way of doing inheritance

Define a class

In JavaScript you can define class like this:

function A(){
    this.aMethod = function (){
        alert("A method");
    }
    this.bMethod = function () {
        alert( "B Method");
    }
}

Yes, yes there are different ways I find this one the most easy one  you can read more about the ways how to create a class in JavaScript here : http://www.phpied.com/3-ways-to-define-a-javascript-class/

Next you have a class how can you use it ?

var a = new A();
a.bMethod(); //will print B method
a.aMethod(); //will print A method

BAM nothing else, easy right?

ok so what if you want to extend this class ?

Prototype Inheritance

First you will create another class:

function B(){
    this.cMethod = function () {
        alert("C method");
    }
}

ok but how can I say that B extends A ? Simple : B.prototype = new A();

Example :

B.prototype = new A();

var b = new B();
b.aMethod(); //will print A method
b.bMethod(); //will print B method
b.cMethod(); //will print C method

Overriding is fine too.

function B(){
    this.bMethod = function() {
        alert("overriding");
    }
    this.cMethod = function () {
        alert("C method");
    }
}

And use it as before ( keep in mind the .prototype = new A is required only ones)

B.prototype = new A();

var b = new B();
b.aMethod(); //will print A method
b.bMethod(); //will print overriding
b.cMethod();// will print C method

Full example:


function A(){
    this.aMethod = function (){
        alert("A method");
    }
    this.bMethod = function () {
        alert( "B Method");
    }
}

function B(){
    this.bMethod = function() {
        alert("overriding");
    }
    this.cMethod = function () {
        alert("C method");
    }
}

B.prototype = new A();

var b = new B();
b.aMethod(); //will print A method
b.bMethod(); //will print overriding
b.cMethod(); //will print C Method

 

Inheritance through Functions

If you don’t like prototypes for some reason you can use a inheritance through functions.

Example:

you just need when you define a class B (the subType) to call this.someFunctionName = supertype and then invoke this.someFunctionName(). Example this.extends = A; this.extends();

Full Example:


function A(){
    this.aMethod = function (){
        alert("A method");
    }
    this.bMethod = function () {
        alert( "B Method");
    }
}

function B(){
    this.extends = A;
    this.extends();
   
    this.bMethod = function() {
        alert("overriding");
    }
    this.cMethod = function () {
        alert("C method");
    }
}

var b = new B();
b.aMethod(); //will print A method
b.bMethod(); //will print overriding
b.cMethod(); //will print C method



UPDATE: Under Internet Explorer if you want to use inheritance through Functions the FUNCTION name that you have to use SHOULD NOT BE "extends" the above example with extends will not work because IE don't like extends :), use some other name like "inheritFrom" for example


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1

[LINUX] How to find a specific String in file content with specific file name in specific folder

Posted by JOKe on 5/19/2011 12:19:00 PM

 

This is really the dumbest thing ever in linux, there are many many dumb things but this is the dumbest. Ultra trivial task you want to “find a specific string in a file content of specific file type starting from root folder” this is the easiest thing ever, it was not available in Windows XP/98 and because of that I was keeping one JBuilder which can search normally in any java file containing XXX in starting from this folder. But in Windows Vista / 7 this is done EASY just press F3! In Linux on the other hand it is a NIGHTMARE I was having a trivial task which takes… 10 seconds to search for a properties file which contains a default.session.timeout=600 which is a row in this file and this took me more then 30 mins because there are TONS of posts how this is done but none have worked there ware examples using grep, egrep whatever NOTHING is working total CRAP really. So in short I found it somewhere and I want to post it in order to have another POST in google which gives the answers.

So In short:

How to search for a file content in linux in specific file names starting from specific root folder.

find . -name "*.properties" -print | xargs grep default.session.timeout=600

Which will give you all properties files which contains default.session.timeout=600 it doesn’t have to be the match the whole row you can search for just default.session which will give you all files which contains default.session. This command is typed in the folder that you want to start the search from for example /opt/hybris/


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2

Generate JavaDoc with UML diagrams

Posted by JOKe on 3/11/2011 12:08:00 PM in

In my life many times has happened when I am assigned to a totally new project that I have no idea what it is about, that has to go live in 2 weeks and that I have to fix some issues in this ultra strange code sometimes even code written in different language.

On my question is there any documentation the answer is: Yes but it is very old or no. So in short they want me to start working on a project with no documentation at all.

My second question is is there a javadoc and the anwer is : yeah … kind of … so I am in a project with 30% javadoc with methods in French language for example ( I don’t know even a single word in French) so in short I am loosing 2 weeks to understand what is using what what is the model what is PersonnePhysique  and what is this crazy domain model.

I believe this has happened with everyone of you at least once so what can you do ?

  • You can start digging into the java code like crazy ( like everyone of us have tried many times)
  • You can install intellij idea and use the great reverse engineering way to create UML diagrams for specific classes but intelliJ idea costs money.
  • You can install netbeans 6.5 and do the same but you have to use this out dated version of NetBeans because this doesn’t exist in newer versions, thanks Oracle.
  • You can install Eclipse + MoDisco + MDT + KML to generate xmisomething file then to generate xml file with KML thingy then to use UML2 tools to view this diagram blah.
  • Or you can find some other way… this is the other way which I believe is very nice and useful and you should use it in every project that you can actually this should be the first thing that the architect should put in the project.

So in short the other way is to generate a UML diagrams each time when a javadoc is generated it will generate a UML diagrams for each class and package which contains whatever you want operations,attributes,constructors just names you can click on them and navigate using them it is AWESOME.

How this will look like ? like this:

uml1

And you can click on items for example on Category which will forward you to the Category javadoc which has a diagram as well which looks like this :

UML2

Awesome right ?

How you can do it ? In my example I will use maven so what you have to do :

use of UmlGraph

use of Graphviz

change of maven pom.xml update (for ant integration check the last link in the blog post)

1) install graphviz on the machine that will generate the javadoc .. usually this is a linux machine which runs hudson or whatever so in case of ubuntu you just need apt-get install graphviz4 otherwise you can download the msi/deb/rpg/source from here http://www.graphviz.org/Download..php then just type “dot –-help” in console to check that the dot executable is in your path.

2) update your pom.xml adding UmlGraph just add:

<plugin>
                <artifactId>maven-javadoc-plugin</artifactId>
                <version>2.7</version>
                <configuration>
                    <aggregate>true</aggregate>
                    <show>private</show>
                    <doclet>org.umlgraph.doclet.UmlGraphDoc</doclet>
                    <docletArtifact>
                        <groupId>org.umlgraph</groupId>
                        <artifactId>doclet</artifactId>
                        <version>5.1</version>
                    </docletArtifact>
                    <additionalparam>
                        -inferrel -attributes -types -visibility -inferdep -quiet -hide java.* -collpackages java.util.* -qualify -postfixpackage
                        -nodefontsize 9
                        -nodefontpackagesize 7
                            </additionalparam>
                </configuration>
            </plugin>

3) invoke mvn javadoc:javadoc … and you are done. :+) easy right ? You can see explanation about all umlgraph options here http://www.umlgraph.org/doc/indexw.html like do you don’t want to see the attributes, but you want the operations and etc..

Example with operations will look like this:

 

For ant integration check http://java.dzone.com/articles/reverse-engineer-source-code-u


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6

Using of Collections.emptyList() the right way in Java 1.5+

Posted by JOKe on 7/27/2010 04:07:00 PM

It is little strange that no one really uses emptyList like he should in Java.
So this is small post showing how to use the emptyList method in the Collections class.

Question: How to create an empty list ?
lets assume that we have a class Book with multiple titles.
So the class in our examples will be:

import java.util.List;

public class Book {

      private List<String> titles;

      public void setTitles(List<String> titles) {

            this.titles = titles;

      }

      public List<String> getTitles() {

            return titles;

      }

}

Lets say that in our snippet we have something like :

  Book myCrazyBook=new Book();

and we want to assign an empty list to the titles in this book. This is a common scenario if you want to set something to be emptyList in specific case instead of null.

So of course your first try will be something like:
Answer 1:

  myCrazyBook.setTitles(new ArrayList()); 

-WARRNING - ArrayList is a raw type. References to generic type ArrayList<E> should be parameterized

Ok changing to:

  myCrazyBook.setTitles(new ArrayList<String>());   

WTF ? the problem in this answer is not small one :
- you are creating empty ArrayList which basiclly is not needed. ( what if you are in a loop 1000+ empty ArrayLists ? )

Answer 2.

   myCrazyBook.setTitles(Collections.EMPTY_LIST);

-WARNING : Type safety: The expression of type List needs unchecked conversion to conform to List<String>, because the EMPTY_LIST is raw type, which was heavily used before Java 1.5.
The definition of this list is :

    /**

     * The empty list (immutable).  This list is serializable.

     *

     * @see #emptyList()

     */

    public static final List EMPTY_LIST = new EmptyList();

So you see it is not ArrayList or LinkedList or MyCrazyCustomListWhichIUseEveryWhereList.

Answer 3:
Eclipse will tell you this answer : Replace with Collections.emptyList();

      myCrazyBook.setTitles(Collections.emptyList());

COMPILE TIME ERROR: why ? because emptyList invoked like that means List of Objects not List of String. The other thing is that you cannot cast to List<String> because you cannot cast List<Object>  to List<String>.

Answer 4:
You know that there is Collections.emptyList() AND YOU KNOW THAT IT RETURNS List<T>
so your answer is:

            Book myCrazyBook=new Book();

            List<String> titles = Collections.emptyList();

            myCrazyBook.setTitles(titles);

           

And this will work WITHOUT any WARNINGS or ERRORS. The type of the List is taken from the type of the variable that you are trying to assign to.
Of course why you need this local variable ? I want to remove it it is not needed and used, but if you remove it you are in Answer 3. So what can you do ?

Answer 5: The right but strange looking answer.

            Book myCrazyBook=new Book();

            myCrazyBook.setTitles(Collections.<String>emptyList());

Yes this is not a joke there is a dot (.) then the generic type before the method name. This compiles, runs, no warnings thats the real way.
It is a little strange that most people dont know this aspect of generics in Java even I didn't know it, I was thinking that you cannot pass a generic type like this but as it looks you can.

So if you have some static method like this one:

public class Main{

      public static <G> List<G> someGreatMethod(){

            List<G> gList= new ArrayList<G>();

            return gList;

      }

}

you can invoke it with Main.<String>someGreatMethod(); for example.

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