Roy Tutorials

@Temporal Annotation In this tutorial I am going to tell you what is the use of @Temporal annotation in JPA (Java Persistence API). @Temporal is a JPA annotation and generally specified only for persistent fields or properties of type java.util.Date and java.util.Calendar. Generally you can use @Temporal annotation on the date or calendar field in entity classes while you are mapping…

Angular Here you will see how to install new Angular framework or update/upgrade the existing Angular version and how to create new Angular project on Windows environment. Related Post: I will use node.js and npm for setting up the new Angular project on Windows environment. If you are using different Operating System then you have to check the installation process…

Composition vs Aggregation explained with Java will show you what is Composition and what is Aggregation? In simple terms, both Composition and Aggregation are Associations. Composition means “Strong Has-A relationship”, whereas, Aggregation means “Weak Has-A relationship”. Composition implies a relationship where the child cannot exist independently without the parent. Example: House (parent) and Room (child). Room doesn’t exist separately without a House….

Spring Boot Data JPA Joins This tutorial will show you Spring Boot Data JPA Left Right Inner and Cross Join Examples. I will show you how to use this example in Spring Boot application, where you will use Spring Data JPA Repository to query your database tables. I will build the project using both maven and gradle build tools. I…

Introduction This example will show you how to segregate positive followed by negative elements in an Array using Java programming language. The elements are integer values here. The function will put all positive numbers first, and then negative numbers and finally count the number of moves required to arrange all elements in the desired order.

FLAK REST CRUD Here you will see Flask REST API CRUD Example. You might have also seen how to create web application CRUD example using Python, Flak and MySQL. REST is an acronym that represents Representational State Transfer. You may also like to read REST APIs in Java and Spring Technologies.

Introduction This tutorial we show you how to connect multiple database servers using Hibernate framework. We know Hibernate is an ORM (Object Relational Mapping) framework for the automated persistence of objects in a Java application to the tables in a relational database. Here we will assume that an application will connect to MySQL and SQLServer databases at the same time….

Introduction In this tutorial we will see how to mock Activiti TaskService, TaskQuery, NativeTaskQuery in Junit class. Suppose you have Spring service class where you are doing some business flow for your application. So you are using Activiti‘s TaskService to create a list of activiti Tasks using the method createNativeTaskQuery(). You may need to create also TaskQuery from TaskService using…

Introduction Here we will see Codeigniter REST + ReactJS CRUD example. We have seen previously Codeigniter REST API examples for GET, POST, PUT and DELETE but here we will see them together. We will use ReactJS as a front-end technology to represent our UI. In this example we will use Codeigniter version 3.1.9 and node version 6.11.3 and npm version 3.10.10. We…

Introduction This example shows you hot to convert milliseconds into days, hours, minutes, seconds in Java. Sometimes you need to convert the milliseconds into days or hours or minutes or seconds. Typically when you want to check the exact time taken to execute a program then you may need to calculate the time. So in this case you get the…