How to apply Checkstyle format automaticaly ?

Problem :


You want to format your code with checkstyle rule with CTRL-ALT-F.




Solution :


Right clic on the project -> Checkstyle -> Create a Formatter


Then go Windows -> Preferences -> Code Style -> Formatter 


Next, you just have to select the formatter you have created.
After that, you can make CTRL - ALT - F to format you code

java 1.8 lambda example

I saw at Devoxx France, a conference about java 1.8 and the use of lambdas by Guillaume Tardif. (http://www.devoxx.com/display/FR12/JDK+8+demo++lambdas+in+Action)

In this article, I will show you an example.You can dowload the jdk here : http://jdk8.java.net/lambda/

To install jdk1.8 on Ubunutu, you can do :


sudo mv ./jdk1.8.0 /usr/lib/jvm/
sudo update-alternatives --install “/usr/bin/java” “java” “/usr/lib/jvm/jdk1.8/bin/java” 1
sudo update-alternatives --install “/usr/bin/javac” “javac” “/usr/lib/jvm/jdk1.8/bin/javac” 1

sudo update-alternatives --config java

Then, you just have to choose the jdk.


Note : I have a bug when I use javac because javac -version show me always 1.6 and not 1.8
So to compile, I've done the following :

/usr/lib/jvm/jdk1.8.0/bin/javac Main.java
java Main

Here is my file Main.java:

import java.util.ArrayList;
import java.util.List;


public class Main {

public static void main(String[] args) {
List names = new ArrayList();
names.add("superman");
names.add("batman");
names.forEach( (String s) -> { System.out.println(s);} );
}

}

Then we show on the screen :

superman
batman


An other important point, Java 1.8 should support multiple inheritance !
If you have comment, post it !

Devoxx FRANCE

Tomorrow it's the beginning of a great conference.

During 3 days, there will be technical session on JAVA, HTML5, NOSQL, CASSANDRA ... et all new technologies !
Go to the web site to see trend of the moment devoxx

Import Existing Maven in Eclipse : project has no J on the folder project

Problem

I made the following :
- Import  Existing Maven project
- Browse -> Choose Maven project (It has pom Module)

Then I saw in Package Explorer, that my project has a M for Maven but has no J for Java Project !
And therefore package are not managed .

Solution 

Right Clic --> Configure --> Convert to facet form

Go : read and write in a file

To read or write in a file, you can use the package io/ioutil which contains méthods like ReadFile orWriteFile

Example :

package main
import ("fmt";"io/ioutil")
func main() {
fmt.Print("Lecture \n");
contents,_ := ioutil.ReadFile("/home/damikde/tmp/server.log")
   println(string(contents))
        fmt.Print("Ecriture \n");
   ioutil.WriteFile("/home/damikde/tmp/toto", contents, 0x777)
}

You can create a free Git open source project by using https://github.com/plans

The content of element type must match

Problem :


I have the following error :
The content of element type "filter" must match  "(icon?,filter-name,display-name?,description?,filter-class,init-param*)".

Here is an extract of my web.xml :
<filter> 
    <display-name>RichFaces Filter</display-name>
    <filter-name>richfaces</filter-name>
    <filter-class>org.ajax4jsf.Filter</filter-class> 
</filter> 


Solution :

In fact, the solution is in the message.The message said that there is an order in the tags filter-mappings.
You have to put first filter-name then url-pattern or servlet name.
So you have to correct like that :

<filter> 
    <filter-name>richfaces</filter-name>
    <display-name>RichFaces Filter</display-name>  
    <filter-class>org.ajax4jsf.Filter</filter-class> 
</filter> 

An important note, this error appear because I put the following dtd in my web.xml :

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>

Or it's not the last dtd.Now it has change and it seems that the good manner is the following :

<?xml version="1.0"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">