Here&#39;s an overview of all RI&#39;s (and alternatives).

### Java Platform, Enterprise Edition 6 (Java EE 6) - [JSR 316][1]
- [Oracle Glassfish 3.x][2] (RI)
- [JBoss AS 6.x and 7.x][3]
- [IBM WebSphere 8.0][4]

### Java Architecture for XML Binding (JAXB) 2.2 - [JSR 222][5]
- [Oracle JAXB][6] (RI, used in Glassfish 3)
- [Oracle Metro][7]

### Java API for XML-Based Web Services (JAX-WS) 2.2 - [JSR 224][8]
- [Oracle JAX-WS][9] (RI, used in Glassfish 3)
- [Oracle Metro][10]
- [Apache CXF 2.x][11]

### Contexts and Dependency Injection for Java - [JSR 299][12] and [JSR 330][13]
- [JBoss Weld][14] (RI, used in Glassfish 3)
- [Apache OpenWebBeans][15]
- [Resin CanDI][16] (JSR299 only)

### Bean Validation 1.0 [JSR 303][17]
- [Hibernate Validator][18] (RI, used in Glassfish 3)
- [Agimatec Validation][19]
- [GWT Validation][20]

### Java API for RESTful Web Services (JAX-RS) 1.1 - [JSR 311][21]
- [Oracle Jersey][22] (RI, used in Glassfish 3)
- [JBoss RESTEasy][23] (used in JBoss AS)
- [Apache CXF 2.x][24]
- [Apache Wink][25]
- [Grails JAX-RS][26]

### JavaServer Faces 2.0 - [JSR 314][27]
- [Oracle Mojarra][28] (RI, used in Glassfish 3)
- [Apache MyFaces 2.0][29]

### Java Servlet 3.0 and JavaServer Pages 2.2/Expression Language 2.2 - [JSR 315][30] and [JSR 245][31]
- [Oracle Glassfish 3.x][32] (RI)
- [Resin 4.0.1+][33]
- [Apache Geronimo 3.0][34]
- [Apache Tomcat 7.0][35]
- [Eclipse Jetty 8.0][36]

### Java Persistence API (JPA) 2.0 - [JSR 317][37]
- [EclipseLink][38] (RI, used in Glassfish 3)
- [OpenJPA 2.0][39]
- [Hibernate 3.5.x][40]

### Enterprise JavaBeans (EJB3) 3.1 - [JSR 318][41]
- [Oracle Glassfish 3.x][42] (RI)
- [Apache TomEE and OpenEJB][43] (EJB 3.1 lite)
- [BuzyBeans][44] (EJB 3.1 lite)


  [1]: http://jcp.org/en/jsr/detail?id=316
  [2]: http://glassfish.java.net
  [3]: http://www.jboss.org/jbossas/
  [4]: http://www-01.ibm.com/software/webservers/appserv/was/
  [5]: http://jcp.org/en/jsr/detail?id=222
  [6]: http://jaxb.java.net/
  [7]: http://metro.java.net/
  [8]: http://jcp.org/en/jsr/detail?id=224
  [9]: http://jax-ws.java.net/
  [10]: http://metro.java.net/
  [11]: http://cxf.apache.org/
  [12]: http://jcp.org/en/jsr/detail?id=299
  [13]: http://jcp.org/en/jsr/summary?id=330
  [14]: http://seamframework.org/Weld
  [15]: http://openwebbeans.apache.org
  [16]: http://code.google.com/p/candi-stripes/downloads/list
  [17]: http://jcp.org/en/jsr/detail?id=303
  [18]: http://www.hibernate.org/subprojects/validator.html
  [19]: http://code.google.com/p/agimatec-validation/
  [20]: http://code.google.com/p/gwt-validation/
  [21]: http://jcp.org/en/jsr/detail?id=311
  [22]: http://jersey.java.net/
  [23]: http://jboss.org/resteasy
  [24]: http://cxf.apache.org/
  [25]: http://incubator.apache.org/wink/
  [26]: http://code.google.com/p/grails-jaxrs/
  [27]: http://jcp.org/en/jsr/detail?id=314
  [28]: http://javaserverfaces.java.net
  [29]: http://myfaces.apache.org/core20/
  [30]: http://jcp.org/en/jsr/detail?id=315
  [31]: http://jcp.org/en/jsr/detail?id=245
  [32]: http://glassfish.java.net
  [33]: http://www.caucho.com/resin-4.0/changes/resin-4.0.1.xtp
  [34]: http://geronimo.apache.org/
  [35]: http://tomcat.apache.org/
  [36]: http://www.eclipse.org/jetty/
  [37]: http://www.jcp.org/en/jsr/detail?id=317
  [38]: http://www.eclipse.org/eclipselink/
  [39]: http://openjpa.apache.org/
  [40]: http://www.hibernate.org/
  [41]: http://jcp.org/en/jsr/detail?id=318
  [42]: http://glassfish.java.net
  [43]: http://openejb.apache.org/
  [44]: http://code.google.com/p/buzybeans/

I have 2 arrays, the value will be loaded from database, below is an example:

    $arr1 = array(1,2,3);
    $arr2 = array(1,2,3,4,5,6,7);

What I want to do is to check if **all the values** in `$arr1` exist in `$arr2`. The above example should be a `TRUE` while:

    $arr3 = array(1,2,4,5,6,7);

comparing `$arr1` with `$arr3` will return a `FALSE`.

Normally I use `in_array` because I only need to check single value into an array. But in this case, `in_array` cannot be used. I&#39;d like to see if there is a simple way to do the checking with a minimum looping.

UPDATE for clarification.

First array will be a set that contains unique values. Second array can contain duplicated values. They are both guaranteed an array before processing.


How can I use in_array if the needle is an array?

I&#39;m vaguely familiar with the &lt;a href=&quot;http://en.wikipedia.org/wiki/Java_Native_Interface&quot;&gt;JNI&lt;/a&gt;, and I&#39;m curious to see my machine-specific implementation for some native methods in the java.lang package. `Thread#currentThread()`, for example.

I&#39;ve found a bunch of DLLs in [JDK_HOME]/jre/bin, but like I said I&#39;m trying to find the source code.

Does anyone know where the native source code can be found? Is it even available, or is it classified by Sun (oops I mean &quot;We&#39;re In It To Win It&quot; Oracle)?

Where to find source code for java.lang native methods?

Do you know if there is a list with all the reference implementation for every component of Java EE 6? I.e. GlassFish is the reference container, Hibernate Validator for validation, etc.


Where can I find a list of all the reference implementations for Java EE 6?

<p>Do you know if there is a list with all the reference implementation for every component of Java EE 6? I.e. GlassFish is the reference container, Hibernate Validator for validation, etc.</p>


In JavaScript this is how we can split a string at every 3-rd character

    &quot;foobarspam&quot;.match(/.{1,3}/g)

I am trying to figure out how to do this in Java. Any pointers?

Splitting a string at every n-th character

How can I find the memory used on my Android application, programmatically?

I hope there is a way to do it. Plus, how do I get the free memory of the phone too?


How do I discover memory usage of my application in Android?

I recently read that making a class singleton makes it impossible to mock the objects of the class, which makes it difficult to test its clients. I could not immediately understand the underlying reason. Can someone please explain what makes it impossible to mock a singleton class? Also, are there any more problems associated with making a class singleton?

mocking a singleton class

I receive following error when I save the object using Hibernate 

    object references an unsaved transient instance - save the transient instance before flushing

 

How to fix the Hibernate &quot;object references an unsaved transient instance - save the transient instance before flushing&quot; error

Given that I have a class Base that has a single argument constructor with a TextBox object as it&#39;s argument. If I have a class Simple of the following form:

    public class Simple extends Base {
      public Simple(){
        TextBox t = new TextBox();
        super(t);
        //wouldn&#39;t it be nice if I could do things with t down here?
      }
    }

I will get a error telling me that the call to super must be the first call in a constructor. However, oddly enough, I can do this.

    public class Simple extends Base {
      public Simple(){
        super(new TextBox());
      }
    }

Why is it that this is permited, but the first example is not? I can understand needing to setup the subclass first, and perhaps not allowing object variables to be instantiated before the super-constructor is called. But t is clearly a method (local) variable, so why not allow it?

Is there a way to get around this limitation? Is there a good and safe way to hold variables to things you might construct BEFORE calling super but AFTER you have entered the constructor? Or, more generically, allowing for computation to be done before super is actually called, but within the constructor?

Thank you.

Is it possible to do computation before super() in the constructor?

I am going through the Java EE 6 tutorial and I am trying to understand the difference between stateless and stateful session beans. If stateless session beans do not retain their state in between method calls, why is my program acting the way it is?


    package mybeans;

    import javax.ejb.LocalBean;
    import javax.ejb.Stateless;

    @LocalBean
    @Stateless
    public class MyBean {

	    private int number = 0;

	    public int getNumber() {
		    return number;
	    }

	    public void increment() {
		    this.number++;
	    }
    }

The client

    import java.io.IOException;
	import javax.ejb.EJB;
	import javax.servlet.*;
	import javax.servlet.http.*;
	import javax.servlet.annotation.WebServlet;
	import mybeans.MyBean;
	import java.io.PrintWriter;
	
	@WebServlet(name = &quot;ServletClient&quot;, urlPatterns = { &quot;/ServletClient&quot; })
	public class ServletClient extends HttpServlet {
		private static final long serialVersionUID = 1L;
	
		@EJB
		MyBean mybean;
	
		protected void doGet(HttpServletRequest request,
				HttpServletResponse response) throws ServletException, IOException {
	
			PrintWriter out = response.getWriter();
			mybean.increment();
			out.println(mybean.getNumber());
		}
	
	}

I was expecting getNumber to return 0 every time but it is returning 1 and reloads of the servlet in my browser increase it more. The problem is with my understanding of how stateless session beans work and not with the libraries or application server, of course. Can somebody give me a simple hello world type example of a stateless session bean that behaves differently when you change it to stateful?




Stateless and Stateful Enterprise Java Beans

In Java, how can you make an `ArrayList` read-only (so that no one can add elements, edit, or delete elements) after initialization?

make ArrayList Read only

How can I upload files to server using JSP/Servlet?

I tried this:

&lt;!-- language: xhtml --&gt;

    &lt;form action=&quot;upload&quot; method=&quot;post&quot;&gt;
        &lt;input type=&quot;text&quot; name=&quot;description&quot; /&gt;
        &lt;input type=&quot;file&quot; name=&quot;file&quot; /&gt;
        &lt;input type=&quot;submit&quot; /&gt;
    &lt;/form&gt;

However, I only get the file name, not the file content. When I add  `enctype=&quot;multipart/form-data&quot;` to the `&lt;form&gt;`, then `request.getParameter()` returns `null`.

During research I stumbled upon [Apache Common FileUpload][1]. I tried this:

    FileItemFactory factory = new DiskFileItemFactory();
    ServletFileUpload upload = new ServletFileUpload(factory);
    List items = upload.parseRequest(request); // This line is where it died.

Unfortunately, the servlet threw an exception without a clear message and cause. Here is the stacktrace:

```lang-none
SEVERE: Servlet.service() for servlet UploadServlet threw exception
javax.servlet.ServletException: Servlet execution threw an exception
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:313)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:637)
```

  [1]: http://commons.apache.org/fileupload





How can I upload files to a server using JSP/Servlet?

I developed a dynamic web project in Eclipse. 
I can access the app through my browser using the following URL: 

    http://localhost:8080/MyDynamicWebApp

I want to change the access URL to:

    http://localhost:8080/app

To do so, I changed the context root from the project &quot;Properties | Web Project Settings | Context Root&quot;.
However, the web app still has the same access URL. I have re-deployed the application on Tomcat and re-started the Tomcat, but the access URL is the same as earlier.

I found that there was no `server.xml` file attached with the `WAR` file. Without the `server.xml` file attached, how is the Tomcat determining that the context root of my web app is `/MyDynamicWebApp` and allowing me to access the application through this context root URL?

How to change context root of a dynamic web project in Eclipse?

I&#39;m starting a new project now. I have to choose technologies. I need something light, so no EJB or Seam. On the other hand I need JPA (Hibernate or alternative) and JSF with IceFaces.

Do you think that such a stack on Spring 3 deployed on Tomcat is a good choice? Or a Java EE 6 web application could be better? I&#39;m afraid that Java EE 6 is a new technology, not well documented yet. Tomcat seems to be easier to maintain than Glassfish 3. 

What&#39;s your opinion? Do you have any experiences?

Java EE 6 vs. Spring 3 stack

I&#39;m developing a Java enterprise application, currently doing Java EE security stuff to restrict access for particular functions to specific users. I configured the application server and everything, and now I&#39;m using the RolesAllowed-annotation to secure the methods:

    @Documented
    @Retention (RUNTIME)
    @Target({TYPE, METHOD})
    public @interface RolesAllowed {
        String[] value();
    }

When I use the annotation like this, it works fine:

    @RolesAllowed(&quot;STUDENT&quot;)
    public void update(User p) { ... }

But this is not what I want, as I have to use a String here, refactoring becomes hard, and typos can happen. So instead of using a String, I would like to use an Enum value as a parameter for this annotation. The Enum looks like this:

    public enum RoleType {
        STUDENT(&quot;STUDENT&quot;),
        TEACHER(&quot;TEACHER&quot;),
        DEANERY(&quot;DEANERY&quot;);

        private final String label;

        private RoleType(String label) {
            this.label = label;
        }

        public String toString() {
            return this.label;
        }
    }

So I tried to use the Enum as a parameter like this:

    @RolesAllowed(RoleType.DEANERY.name())
    public void update(User p) { ... }

But then I get the following compiler error, although Enum.name just returns a String (which is always constant, isn&#39;t it?).

&gt; The value for annotation attribute RolesAllowed.value must be a constant expression`

The next thing I tried was to add an additional final String to my Enum:

    public enum RoleType {
        ...
        public static final String STUDENT_ROLE = STUDENT.toString();
        ...
    }

But this also doesn&#39;t work as a parameter, resulting in the same compiler error:

    // The value for annotation attribute RolesAllowed.value must be a constant expression
    @RolesAllowed(RoleType.STUDENT_ROLE)

How can I achieve the behavior I want? I even implemented my own interceptor to use my own annotations, which is beautiful, but far too much lines of codes for a little problem like this.

**DISCLAIMER**

This question was originally a [Scala][1] question. I found out that Scala is not the source of the problem, so I first try to do this in Java.

  [1]: http://en.wikipedia.org/wiki/Scala_%28programming_language%29


Use Enum type as a value parameter for @RolesAllowed-Annotation

I&#39;m having a tough time understanding how the two interact and where the boundary between them lies. Do they overlap? Are there redundancies between them?

I know there are annotations associated with both, but I haven&#39;t been able to find a complete list for both with brief descriptions. Not sure if this would help clear up how they differ or where they overlap.

Really just confused. I (think I) understand EJB reasonably well, I guess I&#39;m having a hard time understanding exactly what CDI brings to the table and how it supplants or enhances what EJB already offers. 

How do CDI and EJB compare? interact?

I am trying to understand the `javax.inject` package and I am not clear what the `javax.inject.Named` annotation is supposed to be used for. The Javadoc does not explain the the idea behind it. 

Javadoc is at http://download.oracle.com/javaee/6/api/javax/inject/Named.html

I am using **Spring 3.0** to write some sample programs, by putting `@Named` on a bean it seems to add it to the bean factory but the Javadoc description is so light I can&#39;t tell if that is the standard behavior or Spring specific behavior.

My questions are:

 1. What is the difference between `@Named` and `@Qualifier`
 2. How are you supposed to tell the Runtime system a class should be injectable in other classes what&#39;s the annotation for that? The equivalent of `@Component` in Spring?

**Update 1** there is an excellent explanation of `@Named` and `@Qualifier` at Nice article about `@Named` and `@Qualifier` https://dzone.com/articles/java-ee6-cdi-named-components thanks @xmedeko for linking to it the comment below.

What is javax.inject.Named annotation supposed to be used for?

We are planning to write a web application from the scratch, it has been decided to go with the latest edition of Glassfish which complies with Java EE 6 standard, therefore we are analyzing if CDI can be used instead of Spring. 

Can we say that CDI could be a replacement for Spring?

Content Type	Original Author	Original Content on Stackoverflow
Question	Maxime ARNSTAMM	View Question on Stackoverflow
Solution 1 - Java	BalusC	View Answer on Stackoverflow

Where can I find a list of all the reference implementations for Java EE 6?

Java Problem Overview

Java Solutions

Solution 1 - Java

Java Platform, Enterprise Edition 6 (Java EE 6) - JSR 316

Java Architecture for XML Binding (JAXB) 2.2 - JSR 222

Java API for XML-Based Web Services (JAX-WS) 2.2 - JSR 224

Contexts and Dependency Injection for Java - JSR 299 and JSR 330

Bean Validation 1.0 JSR 303

Java API for RESTful Web Services (JAX-RS) 1.1 - JSR 311

JavaServer Faces 2.0 - JSR 314

Java Servlet 3.0 and JavaServer Pages 2.2/Expression Language 2.2 - JSR 315 and JSR 245

Java Persistence API (JPA) 2.0 - JSR 317

Enterprise JavaBeans (EJB3) 3.1 - JSR 318

Where to find source code for java.lang native methods?

How can I use in_array if the needle is an array?

Attributions