NEED simple example JPA CRUD

hi all.. i was noob for JPA.... and i want to make a class where in one class it mount a function to create... delete update and read.... for read and create i was succesfully but for the delete and update queries it was not worked... but the program still run properlly....

here is my sample code


TabelCoba coba=em.find(TabelCoba.class, 1);
utx.begin();
em = emf.createEntityManager();
em.remove(coba);
utx.commit();

what is the mean of the first line where (tabelCoba.class,1); is??

thanks for the kindness