Program Talk

While upgrading from hibernate 3 to hibernate 5, this was one of the issues. Here is how id fields were defined in hibernate 3. @[email protected](strategy=GenerationType.AUTO, generator=”my_seq_gen”)@SequenceGenerator(name=”my_seq_gen”, sequenceName=”MY_SEQ”)private long id; So now, I added allocationSize = 1 to resolve the issue @[email protected](strategy=GenerationType.AUTO, generator=”my_seq_gen”)@SequenceGenerator(name=”my_seq_gen”, sequenceName=”MY_SEQ”, allocationSize = 1)private long id; And for new Ids I used the … [Read more…]

This turned out to be a mistake in the config.  I was using mysql driver. It was a copy-paste mistake. <bean id=”dataSource” class=”org.apache.commons.dbcp2.BasicDataSource”destroy-method=”close”><property name=”driverClassName”><value>com.mysql.jdbc.Driver</value></property>   Here is the correct config: <bean id=”dataSource” class=”org.apache.commons.dbcp2.BasicDataSource”destroy-method=”close”><property name=”driverClassName”> <value>org.postgresql.Driver</value></property>   And the postgres entry in pom.xml : <dependency><groupId>org.postgresql</groupId><artifactId>postgresql</artifactId><version>42.2.23</version></dependency>

The above error is quite obvious that javax.validation is missing. To fix this issue, we would need to import hibernate validator. Here is the dependency to be added to the pom. <dependency><groupId>org.hibernate</groupId><artifactId>hibernate-validator</artifactId><version>6.2.1.Final</version></dependency> Make sure that the version defined above is compatible with hibernate core.

On upgrading Hibernate from version 3 to version 5, I got the above error. Turned out that we were also using Mockito and it also has a dependency on byte buddy. So there was conflict of versions of byet buddy. So here is fix: <dependency><groupId>org.mockito</groupId><artifactId>mockito-core</artifactId><version>2.2.28</version><scope>test</scope><exclusions><exclusion><groupId>net.bytebuddy</groupId><artifactId>byte-buddy</artifactId></exclusion></exclusions></dependency> exclude the byte-buddy jar from mockito.    

Recently we needed to reindex our data due to some changes. Here is how we did it. We defined a file on the file system. If that file is present the reindexing thread runs, so it would easy for our deployment team to run reindexing when needed. Here is the code creating the thread.  So … [Read more…]

Recently we ended up in an issue with enums. One of the developers changed the order of enums because of a change he had to do. And he thought that enum values that are logically together should be put together in enum class also. But when he was done with the change, all the tests … [Read more…]

Have you ever come across a situation that you need to do rate limiting to an api.  In this article we look at one of the ways rate limiting can be done. We would limit access to an api and make only 1 call to api within 2 seconds. This class would use threads and … [Read more…]

In Java scheduling a task to run on fix intervals is quite simple.  Here is the code to create a scheduler