Skip to main content

Dependency Injection

Dependency Injection i.e. Inversion Of Control. I have been asked this question so many times that "What is dependency injection?" so, I felt that I should write something about it..
So what is Dependency Injection?? Dependency Injection is the process of not to create objects explicitly but to describe how they should be created.
As I am working on Spring and Hibernate so this question has been asked for Spring, so how does spring uses it?

In Spring, it uses XML file where we describe how beans(objects) should be created, Spring uses this XML file and creates objects and we simply use these beans in our project.
Consider following scenario,

We have a class

package di.demo;
class A{
     String value;

     public void setValue(String value){
       this.value=value;
     }
}
So we describe this in Spring XML configuration file.

<bean id="aBean"
     class="di.demo.A">
 <property name="value" value="Sachin"/>
</bean>

Spring uses this configuration file, creates a new object for class A and set value for property "value". It uses Reflections for this and this is what Dependency Injection is.

Comments

Popular posts from this blog

Spring AOP : JDK Proxy vs CGLib Proxy

Spring framework is one of the most widely used framework in Enterprise application development. It has so many features such as Dependency injection, Data access integration, MVC, AOP which takes care of most of the boilerplate part of project, and developers can then focus on business logic only. One of the important feature in Spring is AOP. It is used by almost every enterprise application which is being developed using Spring. AOP So what is AOP? Definition of AOP - Aspect oriented programming is a programming paradigm which aims to increase modularity by allowing the separation of cross cutting concerns. Well, my understanding of AOP is - AOP allows us to introduce/join new modules in your project at pre-specified dynamic locations without having to code for it. Traditional examples of AOP is Transaction management, logging etc. You can read more about AOP at here . This article is for those who know AOP, have used AOP in their projects but do not know how Spring or o

Notepad++ Compile and Run Java Programs

Notepad++ is a great file editor. It has many features. The most important feature which I like about Notepad++ is its light weight. It loads up so quickly, that's great. It also provides syntax highlighting for many languages. I use notepad++ to edit general files as well as my simple Java programs. Although notepad++ provides functionality to run external programs, I prefer NppJavaTools plugin to compile and run Java programs using notepad++. You can download NppJavaTools plugin from this page - NppJavaTools . Installation Installation of plugins in notepad++ is very simple process. All you have to do is copy plugin dll into plugins folder of notepad++ installation directory and restart the notepad++. Features This plugin provides following features, Compile and run your Java files within Notepad++ Set custom hotkeys for compiling and running Java Code Library support Compile and Run This function allows you to run your Java programs to compile and run from N

Java Tools Plugin for Notepad++

This post and the plugin is outdated. Please use plugin from this link which is updated and allows customization of shortcut key mappings and much more . Notepad++ is a great free editor. I like notepad++ because its a light weight editor and loads instantly. I use notepad++ for editing many files everyday. One plugin I always wanted was a plugin which lets me compile my java files and execute them from editor itself, but I couldn't find it so I wrote a myself. This plugin can be downloaded from  this link . I am working on this plugin to make it more effective, so that if user have more than one installations of JDK or JRE then user should be able to choose which one to use etc. This is a simple plugin which has two commands- Compile - compiles a java file. Run - executes a java file. For using this plugin Java must be installed on the system.