How to obtain application property values in a Spring Boot application

In this guide, we will discuss two ways to obtain application property configuration values inside a Spring boot application. We will focus on properties that are loaded via an application.properties or an application.yml file. But all loaded properties in your application context should also be obtainable via the discussed methods. We will discuss the @Value …


How to obtain application property values in a Spring Boot application

In this guide, we will discuss two ways to obtain application property configuration values inside a Spring boot application. We will focus on properties that are loaded via an application.properties or an application.yml file. But all loaded properties in your application context should also be obtainable via the discussed methods. We will discuss the @Value …


How to define and declare Spring beans using Java configuration and constructor injection

In this post, we will focus on configuring Spring beans in a Spring-boot environment using Java configuration and constructor injection. This example should be valid for Spring version 4.3 and later. Let us start by discussing a couple of basic concepts.   What is constructor injection?   Constructor injection is the process of injecting Spring …


Reasons why Hamcrest matchers are not so great for Java testing

Hamcrest matchers are great….. not!   When asked why use Hamcrest, developers usually site readability and ease of test writing among the most popular reasons for their choice. In this post, we will break down some of these reasons in order for you to make a better choice of frameworks. We will focus on Hamcrests …


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 …


Mixing property And field javax.persistence annotations causes org.hibernate.MappingException

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 …