persistence

What is the difference between @Column and @Basic annotations in JPA? Can they be used together? Should they be used together? Or does one of them suffice? djna @Basic signifies that an attribute is to be persisted and a standard mapping is to be used. It has parameters which allow you to specify whether the attribute is to be lazily loaded and whether it's nullable. @Column allows you to specify the name of the column in the database to which the attribute is to be persisted. If you specify one without the other then you get default behaviour which is sensible, so commonly folks use only one

i have implement a system to save information about user . So i have aggregation at my class so the user class has list from contact class ...etc in the first page "test it's just for register the user just by phone number " that must save the user in database but this cause error when i deploye my project in Google app engine < 500 server error > and the other page for update the exist user who previously has been registered, so at this will add to the list which the user object has . user class @PersistenceCapable public class User implements Serializable{ @PrimaryKey @Persistent

Here's the situation. My R code is supposed to check whether existing RData files in application's cache are up-to-date. I do that by saving the files with names consisting of base64 -encoded names of a specific data element. However, data corresponding to each of these elements are being retrieved by submitting a particular SQL query per element, all specified in data collection's configuration file . So, in a situation when data for an element is retrieved, but afterwards I had to change that particular SQL query, data is not being updated. In order to handle this situation, I decided to use

What is a good approach to save state of a Java applet? I can deal with object serialization/deserialization to/from a file but don't know where it should be placed or if there's some 'registry' where I can just save a couple of user's settings. Those settings are hardware dependent so I want to save it on client. Full permission is given to the applet. Andrew Thompson What is a good approach to save state of a Java applet? For a trusted applet, there are many options. I can deal with object serialization/deserialization to/from a file but don't know where it should be placed.. Put the

I use JPA 1.0: Query query; query = em.createNamedQuery("getThresholdParameters"); query.setParameter(1, Integer.parseInt(circleId)); List<Object[]> resultList = new ArrayList(); resultList = query.getResultList(); Here I get result as List<Object[]> , thus I have to type convert all the parameters of the row to their respective types which is cumbersome. In JPA 2.0 there is TypedQuery which return an entity object of type one specifies. But as I am using JPA 1 I can't use it. How to get result as Entity object of type I want?? EDIT: QUERY @Entity @Table(name="GMA_THRESHOLD_PARAMETERS")