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POWhy did I get this exception when runnning JPA?
 

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  1. POWhy did I get this exception when runnning JPA?
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    <p>This is just a normal JPA console built by Maven. I got a very annoying exception </p> <pre><code>java.lang.ClassNotFoundException: javax.persistence.Persistence </code></pre> <p>I found some solutions about that such problem and they suggest adding <strong><em>javaee-api</em></strong> lib to pom.xml. But the error still stands with <strong><em>javee-api lib</em></strong>.</p> <pre><code>import javax.persistence.EntityManager; import javax.persistence.EntityTransaction; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; public class App { public static void main( String[] args ) { // This line causes error EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("testjpa"); // It works when I comment above line and print hello } } </code></pre> <p>So I'm pretty sure that the exception doesn't relate to library issues and the persistence.xml file might cause the problem.</p> <p>Here my project tree</p> <pre><code>├── pom.xml └── src ├── main │   ├── java │   │   └── com │   │   └── hoan │   │   ├── App.java │   │   └── Customer.java │   └── resources │   └── META-INF │   └── persistence.xml └── test </code></pre> <p>My persistence.xml</p> <pre><code>&lt;persistence-unit name="testjpa" transaction-type="RESOURCE_LOCAL"&gt; &lt;provider&gt;org.apache.openjpa.persistence.PersistenceProviderImpl&lt;/provider&gt; &lt;class&gt;com.foo.Customer&lt;/class&gt; &lt;properties&gt; &lt;property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/&gt; &lt;property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/quickstart"&gt; &lt;property name="javax.persistence.jdbc.user" value="root" /&gt; &lt;property name="javax.persistence.jdbc.password" value="password"/&gt; &lt;/properties&gt; &lt;/persistence-unit&gt; </code></pre> <p>pom.xml dependencies</p> <pre><code>&lt;dependency&gt; &lt;groupId&gt;org.apache.openjpa&lt;/groupId&gt; &lt;artifactId&gt;openjpa-all&lt;/artifactId&gt; &lt;version&gt;2.0.0&lt;/version&gt; &lt;/dependency&gt; &lt;dependency&gt; &lt;groupId&gt;mysql&lt;/groupId&gt; &lt;artifactId&gt;mysql-connector-java&lt;/artifactId&gt; &lt;version&gt;5.1.22&lt;/version&gt; &lt;/dependency&gt; </code></pre> <p>By the way I followed this thread <a href="https://stackoverflow.com/questions/4261435/no-persistence-provider-for-entitymanager-error">&quot;No Persistence provider for EntityManager&quot; error</a> which has exactly same my problem, but nothing seems to work.</p> <p>Could anyone point me the problem ? Thanks</p> <p>Updated: the command line to run jar file</p> <pre><code>java -cp target/jpa-demo.jar com.foo.App </code></pre>
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    1. CO"So I'm pretty sure that the exception doesn't relate to library issues and the persistence.xml file might cause the problem." - I'm pretty sure you'd be wrong. There's really only one way I know of a `ClassNotFoundError` being caused, and that's by the class not being available anywhere on your classpath. Check the WAR that your build creates, look at the JARs it puts into `WEB-INF/lib/`, and whether `Persistence.class` really is in them? If it's a console app, how are you running it?
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    2. COIn the eclipse I can invoke those such classes without any errors, so I think the nessesary libs were fully loaded
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    3. COThat's not really conclusive. How is your actual program being run? As in, literally, what's the command line used to execute `java`?
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