|By Michael Muller||
|April 26, 2013 10:00 AM EDT||
Hibernate is one of the most used ORM Java frameworks out there. It is really simple to use, just add few annotations and you're ready to go. However, it is also really easy to experience strange behaviors and bugs if you don't respect Hibernate's best practices. That's why at Tocea we developed rules to detect coding mistakes and to make sure that your experience with Hibernate will be painless.
Our Hibernate repository currently contains 30 rules. Some of them are related to the detection of possible bugs, other treat of maintainability or performance. In this article, we're going to present four rules that deal with a famous Hibernate's usage problem : the implementation of equals() and hashCode() methods.
What's the problem?
Equals and hashCode are used to compare objects. The default implementation of equals compares the object's address in memory. This is good as long as your objects are in memory, but Hibernate's goal is precisely to move them out of memory. Within a Hibernate session, Hibernate takes care of managing objects equality between a persistent identity and a Java identity.
However, when dealing with objects that come from different sessions, Hibernate can't do it. That's why it is necessary to override equals and hashCode.
This is our rule n°1 : HbEntitiesMustImplementEqualsHashCode detects any Hibernate entity that does not implement both methods. We also have HbEmbeddableEntitiesMustImplementEqualsHashCodethat does the same for embeddable entities.
First step to solve it : implement equals()
So, I have a User and I want to implement the equals() method. I can just use its Id...
Ooops, or can't I? Indeed, if your Id is generated (as it is likely to be), it will be assigned once the object is persisted. Before that, all non-persisted entities have the same null id. So you could experience strange equality results... The good solution is to rely on the objects business fields to compare them, like the first name and the last name of my user.
This is our rule n°3 : HbEntitiesEqualsMustAvoidIDField detects usage of id field in equals().
Second step to solve it : implement hashCode()
I'm now ready to implement hashCode(). The Java language requires that if a.equals(b), then a.hashCode() is the same as b.hashCode(). As a consequence, I must use the same fields in hashCode() as I used in equals(). This may seem trivial for simple entities, but through evolution of an entity, this can be easy to forget to add a new field to one of the method.
This is our rule n°4 : HbEntityEqualsAndHashCodeUseDifferentFields detects equals and hashCode methods that use different fields.
To sum up, with this four rules you should be able to prevent a good deal of bugs related to incorrect usage of equals and hashCode in Hibernate entities. Have you already encountered such problems? Do you think there should be more rules regarding the implementation of these two methods? Please let us know in the comments!
Oh, and we have presented four of our thirty Hibernate rules, so that leaves plenty of interesting stuff to talk about : stay tuned!
Keeping pace with advancements in software delivery processes and tooling is taxing even for the most proficient organizations. Point tools, platforms, open source and the increasing adoption of private and public cloud services requires strong engineering rigor – all in the face of developer demands to use the tools of choice. As Agile has settled in as a mainstream practice, now DevOps has emerged as the next wave to improve software delivery speed and output. To make DevOps work, organization...
Jul. 30, 2016 12:30 AM EDT Reads: 2,327
Predictive analytics tools monitor, report, and troubleshoot in order to make proactive decisions about the health, performance, and utilization of storage. Most enterprises combine cloud and on-premise storage, resulting in blended environments of physical, virtual, cloud, and other platforms, which justifies more sophisticated storage analytics. In his session at 18th Cloud Expo, Peter McCallum, Vice President of Datacenter Solutions at FalconStor, discussed using predictive analytics to mon...
Jul. 30, 2016 12:30 AM EDT Reads: 2,128
The IoT is changing the way enterprises conduct business. In his session at @ThingsExpo, Eric Hoffman, Vice President at EastBanc Technologies, discussed how businesses can gain an edge over competitors by empowering consumers to take control through IoT. He cited examples such as a Washington, D.C.-based sports club that leveraged IoT and the cloud to develop a comprehensive booking system. He also highlighted how IoT can revitalize and restore outdated business models, making them profitable ...
Jul. 29, 2016 10:15 PM EDT Reads: 2,067
SYS-CON Events announced today that Isomorphic Software will exhibit at DevOps Summit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Isomorphic Software provides the SmartClient HTML5/AJAX platform, the most advanced technology for building rich, cutting-edge enterprise web applications for desktop and mobile. SmartClient combines the productivity and performance of traditional desktop software with the simp...
Jul. 29, 2016 10:00 PM EDT Reads: 1,285
"When you think about the data center today, there's constant evolution, The evolution of the data center and the needs of the consumer of technology change, and they change constantly," stated Matt Kalmenson, VP of Sales, Service and Cloud Providers at Veeam Software, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
Jul. 29, 2016 09:45 PM EDT Reads: 1,496
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 19th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo Silicon Valley Call for Papers is now open.
Jul. 29, 2016 08:00 PM EDT Reads: 2,747
We all know the latest numbers: Gartner, Inc. forecasts that 6.4 billion connected things will be in use worldwide in 2016, up 30 percent from last year, and will reach 20.8 billion by 2020. We're rapidly approaching a data production of 40 zettabytes a day – more than we can every physically store, and exabytes and yottabytes are just around the corner. For many that’s a good sign, as data has been proven to equal money – IF it’s ingested, integrated, and analyzed fast enough. Without real-ti...
Jul. 29, 2016 07:45 PM EDT Reads: 1,180
Actian Corporation has announced the latest version of the Actian Vector in Hadoop (VectorH) database, generally available at the end of July. VectorH is based on the same query engine that powers Actian Vector, which recently doubled the TPC-H benchmark record for non-clustered systems at the 3000GB scale factor (see tpc.org/3323). The ability to easily ingest information from different data sources and rapidly develop queries to make better business decisions is becoming increasingly importan...
Jul. 29, 2016 06:15 PM EDT Reads: 958
SYS-CON Events announced today that 910Telecom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Housed in the classic Denver Gas & Electric Building, 910 15th St., 910Telecom is a carrier-neutral telecom hotel located in the heart of Denver. Adjacent to CenturyLink, AT&T, and Denver Main, 910Telecom offers connectivity to all major carriers, Internet service providers, Internet backbones and ...
Jul. 29, 2016 06:00 PM EDT Reads: 932
Big Data, cloud, analytics, contextual information, wearable tech, sensors, mobility, and WebRTC: together, these advances have created a perfect storm of technologies that are disrupting and transforming classic communications models and ecosystems. In his session at @ThingsExpo, Erik Perotti, Senior Manager of New Ventures on Plantronics’ Innovation team, provided an overview of this technological shift, including associated business and consumer communications impacts, and opportunities it ...
Jul. 29, 2016 05:15 PM EDT Reads: 393
Cloud analytics is dramatically altering business intelligence. Some businesses will capitalize on these promising new technologies and gain key insights that’ll help them gain competitive advantage. And others won’t. Whether you’re a business leader, an IT manager, or an analyst, we want to help you and the people you need to influence with a free copy of “Cloud Analytics for Dummies,” the essential guide to this explosive new space for business intelligence.
Jul. 29, 2016 05:15 PM EDT Reads: 988
You think you know what’s in your data. But do you? Most organizations are now aware of the business intelligence represented by their data. Data science stands to take this to a level you never thought of – literally. The techniques of data science, when used with the capabilities of Big Data technologies, can make connections you had not yet imagined, helping you discover new insights and ask new questions of your data. In his session at @ThingsExpo, Sarbjit Sarkaria, data science team lead ...
Jul. 29, 2016 04:45 PM EDT Reads: 1,251
WebRTC is bringing significant change to the communications landscape that will bridge the worlds of web and telephony, making the Internet the new standard for communications. Cloud9 took the road less traveled and used WebRTC to create a downloadable enterprise-grade communications platform that is changing the communication dynamic in the financial sector. In his session at @ThingsExpo, Leo Papadopoulos, CTO of Cloud9, discussed the importance of WebRTC and how it enables companies to focus...
Jul. 29, 2016 04:15 PM EDT Reads: 1,086
Qosmos has announced new milestones in the detection of encrypted traffic and in protocol signature coverage. Qosmos latest software can accurately classify traffic encrypted with SSL/TLS (e.g., Google, Facebook, WhatsApp), P2P traffic (e.g., BitTorrent, MuTorrent, Vuze), and Skype, while preserving the privacy of communication content. These new classification techniques mean that traffic optimization, policy enforcement, and user experience are largely unaffected by encryption. In respect wit...
Jul. 29, 2016 04:15 PM EDT Reads: 473
ReadyTalk has expanded the capabilities of the FoxDen collaboration platform announced late last year to include FoxDen Connect, an in-room video collaboration experience that launches with a single touch. With FoxDen Connect, users can now not only engage in HD video conferencing between iOS and Android mobile devices or Chrome browsers, but also set up in-person meeting rooms for video interactions. A host’s mobile device automatically recognizes the presence of a meeting room via beacon tech...
Jul. 29, 2016 04:15 PM EDT Reads: 430