java.lang.IllegalStateException: Cannot find a public top-level class named BuchKonkret in /home/hani/NetBeansProjects/Bibliothek/src/entitaetsKlassen/BuchKonkret.java
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator$Generator$ClassGenerator.<init>(JavaPersistenceGenerator.java:510)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator$Generator$EntityClassGenerator.<init>(JavaPersistenceGenerator.java:786)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator$Generator$1.run(JavaPersistenceGenerator.java:425)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator$Generator$1.run(JavaPersistenceGenerator.java:423)
        at org.netbeans.api.java.source.JavaSource.runModificationTask(JavaSource.java:953)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator$Generator.runImpl(JavaPersistenceGenerator.java:422)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator$Generator.run(JavaPersistenceGenerator.java:334)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator.generateBeans(JavaPersistenceGenerator.java:188)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.JavaPersistenceGenerator.generateBeans(JavaPersistenceGenerator.java:174)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.RelatedCMPWizard.createBeans(RelatedCMPWizard.java:363)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.RelatedCMPWizard.access$000(RelatedCMPWizard.java:86)
        at org.netbeans.modules.j2ee.persistence.wizard.fromdb.RelatedCMPWizard$1.run(RelatedCMPWizard.java:275)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)