The import javax.persistence cannot be resolved - eclipse

I'm currently working on a project that requires EntityManager EntityManagerFacotry and Persistence each from the javax.persistence package. It seems to be for the database service, but the current code is not very well documented. By searching google it seems that there should be an xml file that comes along with this, but there isn't one of those either. I guess my question is simply how do I make these unresolved imports go away? Do I have to add another jar to the build path? It seems that I shouldn't have to since it's been around since 1.5.
Any help is greatly appreciated.

I ran into this same issue and realized that, since I am using spring boot, all I needed to do to resolve the issue was to add the following dependency:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

Yes, you will likely need to add another jar or dependency
javax.persistence.* is part of the Java Persistence API (JPA). It is only an API, you can think of it as similar to an interface. There are many implementations of JPA and this answer gives a very good elaboration of each, as well as which to use.
If your javax.persistence.* import cannot be resolved, you will need to provide the jar that implements JPA. You can do that either by manually downloading it (and adding it to your project) or by adding a declaration to a dependency management tool (for eg, Ivy/Maven/Gradle). See here for the EclipseLink implementation (the reference implementation) on Maven repo.
After doing that, your imports should be resolved.
Also see here for what is JPA about. The xml you are referring to could be persistence.xml, which is explained on page 3 of the link.
That being said, you might just be pointing to the wrong target runtime
If i recall correctly, you don't need to provide a JPA implementation if you are deploying it into a JavaEE app server like JBoss. See here "Note that you typically don't need it when you deploy your application in a Java EE 6 application server (like JBoss AS 6 for example).". Try changing your project's target runtime.
If your local project was setup to point to Tomcat while your remote repo assumes a JavaEE server, this could be the case. See here for the difference between Tomcat and JBoss.
Edit: I changed my project to point to GlassFish instead of Tomcat and javax.persistence.* resolved fine without any explicit JPA dependency.

If anyone is using Maven, you'll need to add the dependency in the POM.XML file. The latest version as of this post is below:
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.1-api</artifactId>
<version>1.0.0.Final</version>
</dependency>

hibernate-distribution-3.6.10.Final\lib\jpa : Add this jar to solve the issue. It is present in lib folder inside that you have a folder called jpa ---> inside that you have hibernate-jpa-2.0-1.0.1.Final jar

When I ran into this problem, I tracked down enough to fix my problem and move on.
The short version is:
At some point in time Oracle open-sourced J2EE code and the Eclipse foundation took it over.
The transition took a while so information came out during the transition which was transitory in nature. As a result, you might find articles that were only useful during the transition.
The javax.persistence package was moved to a newly named dependency (jakarta.persistence. The persistence package is part of the larger JPA (Java Persistence API). See Intro to JPA.
The Java Persistence API was first released as a subset of the Enterprise JavaBeans 3.0 specification (JSR 220) in Java EE 5. It has since evolved as its own spec, starting with the release of JPA 2.0 in Java EE 6 (JSR 317). JPA was adopted as an independent project of Jakarta EE in 2019. The current release as of this writing is JPA 3.1.
There were issues with SpringBoot pulling in multiple javax.persistence dependencies, Spring-Boot Issue 21220.
Spring and SpringBoot updated their dependencies to use the new location. From Infoq.com, Nov 24, 2022
VMware released the long-anticipated Spring Framework 6 and Spring Boot 3. After five years of Spring Framework 5, these releases start a new generation for the Spring ecosystem. Spring Framework 6 requires Java 17 and Jakarta EE 9 and is compatible with the recently released Jakarta EE 10
If you are on this page looking for answers, most likely it's because your code doesn't compile because it can't find javax.persistence. If this is the case, then you'll either need to:
add the dependency to jakarta.persistence.
Or use older versions of Java and JPA dependencies define classes in the javax.persistence package.
In the future or if you choose to you can rename references from javax.persistence to jakarta.persistence. The same class files in javax.persistence also exist in the jakarta.persistence package.
To fix my problem I added the following dependency:
<dependency>
<groupId>jakarta.persistence</groupId>
<artifactId>jakarta.persistence-api</artifactId>
</dependency>
I was using SpringBoot 2.2.2.RELEASE af the time which picked up version 2.2.3 of the jar file (jakarta.persistence-api-2.2.3.jar).
This jar file contained (at least) the following packages:
javax.persistence
javax.persistence.criteria
javax.persistence.metamodel
javax.persistence.spi
based on what my IDE is telling me.
The following articles were helpful for me to get to the solution I needed:
The SO question about this and the answer - https://stackoverflow.com/a/60024749/3281336 which pointed to links I've also included below. Thanks to #Krisz for that.
Explanation of why javax.persistence package was moved to jakarta dependency - https://blogs.oracle.com/javamagazine/post/transition-from-java-ee-to-jakarta-ee This article is good because it gives old dependencies along with the newer dependencies that are needed
SpringBoot 3 & Spring Framework 6 use Jakarta EE 9 - https://www.infoq.com/news/2022/11/spring-6-spring-boot-3-launch/

My solution was to select the maven profiles I had defined in my pom.xml in which I had declared the hibernate dependencies.
CTRL + ALT + P in eclipse.
In my project I was experiencing this problem and many others because in my pom I have different profiles for supporting Glassfish 3, Glassfish 4 and also WildFly so I have differet versions of Hibernate per container as well as different Java compilation targets and so on. Selecting the active maven profiles resolved my issue.

I solved the problem by adding the following dependency
<dependency>
<groupId>javax.persistence</groupId>
<artifactId>persistence-api</artifactId>
<version>2.2</version>
</dependency>
Together with
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jdbc</artifactId>
</dependency>

If you are using Gradle with spring boot and spring JPA then add the below dependency in the build.gradle file
dependencies {
compile group: 'org.springframework.boot', name: 'spring-boot-starter-data-jpa', version: '2.1.3.RELEASE'
}

In newer hibernate jars, you can find the required jpa file under "hibernate-search-5.8.0.Final\dist\lib\provided\hibernate-jpa-2.1-api-1.0.0.Final". You have to add this jar file into your project java build path. This will most probably solve the issue.

Add this to your dependency if your using maven
<dependency>
<groupId>javax.persistence</groupId>
<artifactId>javax.persistence-api</artifactId>
<version>2.2</version>
</dependency>

If you are using Hibernate as a JPA implementation and you are not using Maven/Gradle, the easier way is to download whole bundle instead of jar file one by one.
Go http://hibernate.org/orm/downloads/ and download the latest library, extract the jar from the required folder.

Sad and ashamed to say that after spending 1 hour on same problem (unable to resolve #Entity and javax.persistence) occurring on STS/Eclipse and with all the imports (implementation 'org.springframework.boot:spring-boot-starter-data-jpa'). Turns out it was issue with STS/Eclipse IDE because exactly same code worked on IntelliJ IDE. If nothing works give another IDE a go.

If you are not using Maven/Gradle to import the dependency, simply just download this jar from maven repository and set in build path on Eclipse or your preferred IDE.
https://mvnrepository.com/artifact/javax.persistence/javax.persistence-api/2.2

Related

Class not found when using JAX-RS with Eclipse and Glassfish

I am using Eclipse Luna (versions 4.4.2) and Glassfish 4 to build a REST web-app using JAX-RS.
The following piece of code, which is just a very simple post to the REST api that was previously working just fine, has started throw a very strange error:
#POST
public Response addToWatchlist(WatchlistEntry watchlistentry)
{
return Response.ok(watchlist_service.addToWatchlist(watchlistentry).toString()).build();
}
The error is below:
Warning: StandardWrapperValve[Jersey Web Application]: Servlet.service() for servlet Jersey Web Application threw exception
java.lang.ClassNotFoundException: javax.xml.parsers.ParserConfigurationException not found by org.eclipse.persistence.moxy
All I have been able to find out about this is this webpage:
https://java.net/jira/browse/JERSEY-2888
One of the comments says this has been fixed in EclipseLink 2.6.1 and Jersey 2.19.
I am pretty new to using MAVEN and eclipse - assuming the above is correct, how do I get my Maven Project in Eclipse to update the Jersey version? Also how do I update the EclipseLink version? Their site only seems to have version 2.6.0 available: http://www.eclipse.org/eclipselink/#download
I assume all this can be done through eclipse itself?
All help appreciated!
EDIT 1: It seems like eclipselink 2.6.1 has been released on Oct 15th 2015, as you can see here: http://www.eclipse.org/eclipselink/releases/
However, as you can see here, it doesn't seem to have been incorporated into eclipse for "help -> update software": http://download.eclipse.org/rt/eclipselink/updates/
Which is highly annoying.
I am building my REST website, and no PUT or POST will work because of this error.
Does anybody know how to get 2.6.1 working? I am using a Maven jersey-quickstart-webapp Project.
This bug is a royal pain in the face.
EDIT 2: I've got a hack working today. When I check programmtically what version of eclipselink is being used at runtime like below, it tells me it is version 2.6.1, even though the bug remains:
Class<?> myClass = Class.forName("org.eclipse.persistence.Version");
Method myMethod = myClass.getMethod("getVersion");
String version = myMethod.invoke(null).toString();
System.out.println("version = " + version);
In a related question (How to find what version of EclipseLink my Eclipse Project is using?) I found out how to find the actual jar files glassfish is using for eclipse. They are in the glassfish/modules directory. Inside the org.eclipse.persistence.core.jar file has will be a readme.html which tells you the version of eclipselink that glassfish is using. For me it was 2.6.
I manually updated the org.eclipse.persistence.core.jar and the org.eclipse.persistence.moxy.jar file with the latest versions from the maven site. While this is quite hacky, as I don't know what else is effected by doing this, it does get over this problem. If I find out the correct way to do this, I will write an answer below, for all and sundry.
Going through the Jersey JIRA and eclipse link website it seems like Eclipse link 2.6.1 is still under development i.e. not yet released. That's why its not available for download.
To use an updated version of Jersey in maven you need to give depending to the newer version 2.19 in your pom.xml.
But, since eclipse link 2.6.1 is yet to be released, even if you use newer version of Jersey it might be of little use. But still you can give it a try.
To update version of jersey, find the following dependency and update the value of version tag in your pom.xml file
<dependency>
<groupId>org.glassfish.jersey.core</groupId>
<artifactId>jersey-server</artifactId>
<version>2.22.1</version>
</dependency>
Which server are you deploying your project into? I've had A LOT of problems with Glassfish 4.1.1 (incluiding that error). I downgraded to 4.1 and everything runs fine. It may be due to a problem with 4.1.1 newest modules (jars incluided in the server). I hope it helps. Its not the best solution but for me was a temporary workaround 'till I find which modules are failing.
The problem was solved by updating the version of eclipselink that glassfish was using. Eclipse updated it's version, but glassfish needs it's own update. The list of jar files that need to be placed in the glassfish/modules directory is given in this answer: How to change EclipseLink in GlashFish 4.0?

M2E WTP Copy Provided Jar

I have a custom classloader jar <scope>provided</scope> that must be in tomcat/lib before my webapp is run or else it fails to start. I'm using WTP. Is there some way that I can configure M2E/WTP to automatically copy this custom jar to tomcat/lib during the deploy process?
Edit:
It doesn't have to be using WTP, I could also use, for example, a solution using tomcat6-maven-plugin.
For running an embedded Tomcat instance with the Tomcat Maven plugin, add the JARs required in the Tomcat lib dir as dependencies of the Tomcat plugin itself as shown in this example with the derby and javamail dependencies.
I spent a lot of time researching this problem and here's what I've found:
The tomcat6-maven-plugin does not properly emulate the tomcat boot order, as seen in this jira issue as well as their tomcat6-maven-plugin source.
However, after more research I discovered another maven plugin that I didn't know existed: cargo. Thanks to their excellent documentation I was able to get my project running with the custom (and picky) class loader jar.

How to add HSQLDB library to SpringMVC in Maven?

I would like to ask how to add HSQLDB library hsqldb.jar in Maven? I have project in Eclipse created as Spring Template Project from SpringSource Tool Suite. It uses Maven as far as I know. I would like my project to use and work with HSQL database. And at this moment I want my Tomcat server to use HSQLDB library file. So If I added this library file in Maven, my project would work properly with HQL database. This is my assumption.
I have found this example http://slu.livejournal.com/5965.html but adding the jar file to the class path isn't very good programmig practice, is it?
I'm newbie in Maven and also in Spring Framework.
Newest version:
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>2.2.8</version>
<scope>runtime</scope>
</dependency>
Remember about runtime scope in such artifacts (most people forget about it), since you use some generic API/SPI (ORM or JDBC probably) for database access and HSQLDB is only some kind of vendor for run-time implementation of such API/SPI.

Maven and dependency

I cannot quite understand what we need maven for and what dependency is.
Could anyone explain in simple words what means? Where does it look for them?
When writing:
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>2.0.0</version>
</dependency>
It tells:
Missing artifact org.eclipse.persistence:eclipselink:jar:2.0.0
What does it mean?
I have 2 versions of maven installed on my system - one for the cmd, the second one as a plugin for eclipse. What is the difference? Which way is it more common to use Maven - from the cmd or from eclipse?
And I read somewhere that maven needs connection to the internet - what is that for?
I guess you are newbie to Maven, I would suggest you to go through the following links
What is Maven?
DeveloperWorks article
Article in Java World
More Maven articles
Maven is a build tool (like ant) which can pull specific versions of libraries and other dependencies from an online server. If you want to use methods which are in a library (even an older version of it) you don't need to install the library on your computer, maven will grab the specified version and store it for you. You can even have two projects which use two different versions of the same library and not have any conflicts, as maven will handle all the libraries for you.
The code you have specifies that you will be using version 2.0.0 of the eclipselink library. Maven will search for that version of that library, first in its cache of libraries and then in the online database, and compile your code along with the library, so your classes have access to the library methods.
I don't think either the command line or eclipse plugin are more popular - I use mostly command line but have both installed.
As to why maven is indicating that your dependencies is missing, you can use http://mvnrepository.com to find dependencies in the maven central repository. Searching for "org.eclipse.persistence" reveals that might actually be needing:
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>javax.persistence</artifactId>
<version>2.0.0</version>
</dependency>

Unable to find interface javax.transaction.UserTransaction;

I am trying to setup a new Netbeans project with JPA. The Java SDK version is 1.5.0_22-b03 and J2EE version is J2EE 1.4.I am using TOPLINK Essentials for JPA.
Going by javadoc javax.transaction.UserTransaction interface comes with J2EE 1.4.
Then why it's not able to find javax.transaction.UserTransaction?
The JPA 1.0 specification is meant to cater to Java EE 5 containers and not J2EE 1.4 containers (unless the same also support EJB 3.0 like the erstwhile OC4J containers from Oracle). Likewise JPA 2.0 caters to Java EE 6 containers.
I would suggest using Netbeans with Java EE 5 or Java EE 6, instead of heading for a wild goose chase on getting your JPA 1.0/2.0 provider to work amicably with a J2EE 1.4 container. This isn't merely about placing some JARs in your compile time classpath; your runtime classpath will require classes that are available only in a Java EE 5/6 container.
Either you have an incorrect classpath or you are missing a required jar. What are you using to build?
You have not correctly included the j2ee-1.4.jar in your project classpath. Otherwise you can reference to it. Perhaps you meet problem in setting classpath of your java project in netbeans.
Please check your jar to ensure it is correctly downloaded.
Maybe this is an old question but since no other answer has been posted, I post what I was able to do to make it work.
I found a file at:
C:\Program Files (x86)\NetBeans 8.1\java\modules\ext\hibernate4
Right-click your project >Libraries >Add jar > find your Netbeans installation directory...
usually => C:\Program Files (x86)\NetBeansXXX
find java\modules\ext\hibernate4 and choose jboss-transaction-apixxxxx.jar
hope it helps everyone else,