Thread: PreexistingEntityException error in NetBeans

I am trying to create a Java application using Netbeans 8.2 for a uni project. I'm having an issue after creating a JFrame form for adding some data to the database.
NetBeans highlights the final statement "ujc.create(u2);" in the code segment below with the following error message: 'Unreported exception PreexistingEntityException; must be caught or declared to be thrown'
Can someone advise what I need to do to fix this issue as I have no idea what I'm doing wrong.

   private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)                                         
   {                                             
      Users u2 = new Users();
      u2.setEmployeeno(jTextField1.getText());
      u2.setFirstname(jTextField2.getText());
      u2.setSurname(jTextField3.getText());
 
      EntityManagerFactory emf = Persistence.createEntityManagerFactory(
              "BatteryManagementSystemPU");
      UsersJpaController ujc = new UsersJpaController(emf);
      ujc.create(u2);  
   }

My problem is now solved using try/catch statement