Author: iba
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Troubleshooting a PropertyNotFoundException in JPA
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 on!. Let us…
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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…
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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 the number…
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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 user can have…
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How to manage JPA bidirectional relationships properly
In this troubleshooting guide, we will explore how to properly map bidirectional relationships and common mapping pitfalls that cause exceptions such as DataIntegrityViolationException, a ConstrainViolationException and a PropertyValueException. We will take an unusual approach in this guide by first building the faulty software, and then we will discuss how and why this should be fixed.…
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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 previous post, we discovered…
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org.hibernate.MappingException: Could not determine type for: java.util.List – Causes & Fixes
In this post, we will explore a very common Hibernate error, namely a MappingException caused by missing annotations on the Entity getters and fields. The error Let us check the following stack trace as an example: java.lang.IllegalStateException: Failed to load ApplicationContext Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘entityManagerFactory’ defined in class path resource…
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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 that defines how data…
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Configure MBeans in Spring boot using Java config and Jolokia
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). Before we start, I highly recommend that you also check our Jolokia and Spring boot tutorial before you proceed as it will make understanding this post much…
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How to configure Jolokia on a Spring boot server
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. Jolokia is a JMX over HTTP bridge that allows system administrators to access their MBeans and JMX functionalities over HTTP and JSON. Getting…