9 Reasons for keeping software dependencies up to date

In this post, we will explore nine reasons why keeping software dependencies up to date is a very important task, and why it should be part of every software developer’s work routine.   Keeping software secure   Upgrading your software dependencies does not only provide you with the latest and greatest features and APIs, but …


JPA / Hibernate PropertyNotFoundException – Troubleshooting and fixes

      In this post, we discuss yet another reason for having a mapping error from Hibernate. This specific one is called a PropertyNotFoundException. If you have made sure that your property is correctly mapped to the database table, with correct column names and a getter and a setter for the property, then read …


Java – Convert a decimal number to and from a binary number

In this tutorial, we will discuss how to convert a decimal number to binary and back to a decimal. This can easily be done by preexisting Java functionalities. But for the sake of curiosity, let us implement our own algorithm first, and then let us discuss how to do with existing Java functions.   Algorithm …


Java Modulus / Modulo operator – Examples and Uses

The Java modulus ‘%’ operator is one of numerous operators built into the Java programming language. The operator is used to calculate the remainder of the division between two numbers. First, let us discuss how the operator works.   How to use the ‘%’ operator:   The ‘%’ operator requires two operands. The first is …


JPA / Hibernate – Mapping One-to-One relationships

  In this tutorial, we will discuss how to map and configure One-to-One relationships in JPA and Hibernate.   What are One-To-One relationships?   One to One relationships in databases define the relationship between two different entities, where the first entity can be related to zero or one of the second entity. For example, a …


DataIntegrityViolationException & ConstraintViolationException- Managing JPA bidirectional relationships properly

Troubleshooting DataIntegrityViolationException,  PropertyValueException & ConstraintViolationException – Managing JPA bidirectional relationships properly   In this troubleshooting guide, we will explore one of the most common causes of a DataIntegrityViolationException, a ConstrainViolationException and a PropertyValueException. We will set up our database tables and our entity models in order to reproduce the exception, and then we will discuss how the …


Configuring and mapping database tables to JPA entities

  In this post, we will explore how to map a database tables to JPA Entities. In our example, we will use a Spring Boot environment, JPA 2.2 and Hibernate 5.3.7 . However, the information presented here should apply to any environment with a JPA version of 2.1 or later.   Introduction:   In our …


org.hibernate.MappingException: Could not determine type for: java.util.List – Causes & Fixes

The error: In this post, we will explore a very common Hibernate error, namely a MappingException caused by missing annotations on the Entity getters and fields. Let us check the following stack trace as an example:  

  The implementation:   Now let us take a look at the code. The implementation contains two …


Getting started with Spring boot 2 and JPA

  In this tutorial, we will build a simple Spring boot 2 application with access to a Postgres database using JPA.   Background:   Before we get started, let us get a couple of definitions out of the way.   What is JPA? JPA stands for the “Java Persistence API”. It is a java specification …


Create, configure and test an MBean in Spring boot using Java config and Jolokia

Summary: In this article, we will create a new custom MBean. We will show how to configure this bean and then we will test it using Jolokia (JMX over HTTP).   Prerequisites: If you have not yet configured Jolokia, then we suggest that you go over this article https://nullbeans.com/how-to-configure-jolokia-on-a-spring-boot-server/ before you proceed.   Introduction: Managed beans (MBeans) …


How to configure Jolokia on a Spring boot server

Summary:   In this article, we will find out how to configure Jolokia on a Spring Boot 2 server. We will also configure Jolokia on a different management port and a different base URL.   Background:   Jolokia is a JMX over HTTP bridge that allows system administrators to access their MBeans and JMX functionalities …