Huong Dan Java - Page 66 of 76 - Java development tutorials

Using @OneToMany annotation in JPA

Suppose, you are working on a project where the database has two tables, such as student and clazz, structured like below:

CREATE TABLE `clazz` (
  `id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `student` (
  `id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `clazz_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  FOREIGN KEY (`clazz_id`) REFERENCES `clazz` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `clazz` (

`id` int(11) NOT NULL,

`name` varchar(255) DEFAULT NULL,

PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `student` (

`id` int(11) NOT NULL,

`name` varchar(255) DEFAULT NULL,

`clazz_id` int(11) DEFAULT NULL,

PRIMARY KEY (`id`),

FOREIGN KEY (`clazz_id`) REFERENCES `clazz` (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

As you can see, the clazz table has columns id and name with the primary key id. Student table has columns id, name… Read More

Bind request parameter with method argument using @RequestParam annotation in Spring MVC

8 years ago by Khanh NguyenSpring MVC

Using the @RequestParam annotation along with the @RequestMapping annotation we can bind the parameter request with the method argument in Spring MVC. How is it in details? We will find out in this tutorial. Assuming now, we need to build a Controller to handle the… Read More

Using @ManyToOne annotation in JPA

8 years ago by Khanh NguyenJPA

Annotation @ManyToOne in JPA is used to express multiple-to-one relationships between two tables in a database. There are many records in table A related to a record in table B. For example: many different students may have the same class. In this tutorial, we will… Read More

Using @OneToOne annotation in JPA

8 years ago by Khanh NguyenJPA

In JPA, to express one relationship to another, for example, a tourist can have a single room in a large hotel, we will use the @OneToOne annotation. How is it in details? In this tutorial, let’s learn about annotation @OneToOne in JPA! First, I will… Read More

JPA and Spring framework

8 years ago by Khanh NguyenSpring Basic

In JPA, the EntityManagerFactory object is an entity management object that manages the connection to the database. Using Spring to manage this object will help us a lot in developing Java applications that use JPA. In this tutorial, I will guide you on how to… Read More

Some ways to initialize Optional object in Java

8 years ago by Khanh NguyenJava Basic

In the previous tutorial, I introduced with you all about the Optional object in Java. In this tutorial, let’s find out some ways to initialize your Optional object in Java. OK … First, we can initialize an Optional object with the nulled reference variable. For… Read More

Inversion of Control and Dependency Injection

8 years ago by Khanh NguyenDesign Pattern

In the previous tutorial, we looked at what Dependency Injection is. So, in this tutorial, we will go into Inversion of Control (IoC), and find out the relationship between these two concepts. As I said, with Dependency Injection, an object does not depend on another… Read More

Deploy Spring Boot application in Docker

8 years ago by Khanh NguyenDocker

In this tutorial, I will guide you on how to deploy a Spring Boot application in Docker. The steps, we need to take, are: Create a simple Spring Boot project. Write Dockerfile Deploy the application to the Docker Container. OK, let’s get started. Create a… Read More

Change Java version in macOS

8 years ago by Khanh NguyenJava Basic

Assume, you are installing multiple Java versions in macOS, so how do you change from one version to another? In this tutorial, I will guide you to do this. First, let’s open Terminal and enter the following command to check all the Java versions that… Read More

Some important concepts of Docker

8 years ago by Khanh NguyenDocker

In this tutorial, I will talk about some important concepts of Docker that anyone, who wants to work with Docker, needs to know and distinguish them. These concepts include: Image Image is an immutable template that defines components, applications will be installed in a Docker… Read More