Java

Let’s take an example & understand the problem first. We have one VehicleService interface: We have two different implementations of VehicleService: We have a RestController: So you got the problem. I need to use either TwoWheelerService or FourWheelerService based on the “type” query parameter in the Controller method. We can do that easily. We can … Read more

Let me explain the problem first. We have a Java class under test. We are using Junit with Mockito framework to write the unit test cases.We have annotated our test class with @InjectMocks annotation as below: @InjectMocks private TestClass testClass; @Mock private Dependency1 dependency1; @Mock private Dependency2 dependency2; That should inject mocked dependencies to the … Read more

We are fond of one db session per request pattern. For web applications with JPA & Hibernate, it is good strategy in common cases. But for some long-running requests (definition of long-running depends on your use case, maybe 500 ms or 2 s), we need to tweak when we are actually acquiring a db connection … Read more

If you are using JPA or Hibernate directly and got that exception while starting your application, there is one obvious reason for that. You forgot to add that table in MySQL database or any other database that you are using. But if the table is present, then most likely it is a database user permission … Read more

Well, practically there is not much difference. If you check Java doc, you will notice that Closeable interface extends AutoCloseable interface. But there is one difference & that explains the reason why AutoCloseable interface was introduced in Java 7. Closeable  close() method can throw IOException only. And that made  sense as you will be using … Read more

If you have come to this post, then you are facing xml parsing issue in Java. Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.         at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:203) One common issue for this is BOM character. So what is a BOM (BYTE ORDER MARK) character? When you have … Read more

If you are here, that means probably you have encountered below error: Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target         at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)         at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)         at sun.security.validator.Validator.validate(Validator.java:260)         at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)     … Read more