java


Introduction This is the second post on the series about Spring Bean Scopes. In the previous tutorial we saw that there were issues rising when a Prototype scoped Bean was injected in a Singleton scoped Bean. The main problem is that autowired Prototypes will be injected when the Singleton Bean is instantiated (which happens only once) thus even though they are prototypes in reality they’ll behave as singletons. The next code highlights this behavior: [crayon-5ba2d64c1634c927381848/] In the previous example, although the object requested with getAutowiredSample is defined with a Prototype scoped Bean, the instance of the object returned in both […]

Spring Bean Scopes: Singleton with Prototypes


Introduction This tutorial shows the different scopes you can assign to a Bean or a Component in Spring Framework. It’s important to understand that a Bean definition is just a recipe to create instances of a class following the definition of this recipe. This recipe can be then used one or more times during the life cycle of the application to create an instance of the Bean. The Bean scope is one of the main characteristics of the Bean configuration in Spring. The scope will indicate when and how is the object for the Bean definition going to be instantiated. […]

Spring Bean Scopes: Guide to understand the different Bean scopes


Java 10
Introduction As you probably already know, Java 10 was released the past 20th of March following the new tight six-month release schedule. This version comes just after the Java 9 release on September 2017 and marks this past release obsolete. Same will happen to Java 10 on September this year, when the release of Java 11 will mark this one obsolete. Java 11 will be released as a long term support (LTS) version and will have a much longer lifespan, but until then, let’s take a look at some of the new features in Java 10. Time-Based Release Versioning Java […]

Java 10: Testing the new release



Java 8 Streams
Introduction In this post we’ll see how to use Java Streams introduced in Java 8 to obtain a Map from a List. Maps are data structures composed of a collection of key-value elements such that a key is unique within the collection. This allows us to perform searches to find an element with a given key really quickly, without the need to iterate through the full collection. It’s a really common situation that when we have to solve a problem where the start point is a list of elements, we need to convert this list to a map so that […]

Java 8 Streams: Convert List into Map


Spring-Data + MongoDB 2
Introduction Spring Data makes really quick and easy the process of working with data entities, offering a specific implementation for MongoDB. You can merely define queries by creating interfaces with methods following a naming convention or annotating them with @Query and Spring will automagically generate an implementation for you. Most of the times this is enough for simple CRUD and query operations and there is no need to define additional methods. This will allow you to get up and running really quickly avoiding to type boilerplate code. However, there are many times where this is not enough and the repository […]

Spring Data MongoDB: Custom repository implementation


Introduction When running a static code analysis tool or inspecting/analyzing your code from your IDE, you may have encountered the following warning regarding your @Autowired fields: Field injection is not recommended This post shows the different types of injections available in Spring and what are the recommended patterns to use each of them. Injection types Although current documentation for spring framework (5.0.3) only defines two major types of injection, in reality there are three; Constructor-based dependency injection Setter-based dependency injection Field-based dependency injection The latter is the one which the static code analysis tool complains about, but is regularly and […]

Field injection is not recommended – Spring IOC



build.gradle script 5
Introduction In this post I’ll show you how to serve an Angular (>2) frontend application using a Java Spring Boot application as the backend and static page web server, and a Gradle script to perform automated build and deploy tasks both for Spring and Angular. Requirements The technology stack required for this tutorial is: Node.js Angular CLI Gradle The main goal is to achieve a npm install + build that integrates with Java’s gradle build and deploys the distribution files into Spring’s static resources directory. You could replace Angular CLI for any other Frontend build tool / framework such as React. […]

Angular + Spring Boot integration using Gradle


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Since the release of NetBeans 6.0, BeansBinding (JSR 295) framework popularity has increased. Personally I’m using it now in all my projects. Ease of development and the increase of productivity are worth it. The counterpart is that this project looks dead and hasn’t been updated for more than a year now. Even more, recent news about Swing core is not very encouraging. In my opinion I believe that Sun’s budget is very limited and their recent javaFx has consumed all their resources in the past year. Bearing in mind that BeansBinding is now included in netbeans and that javaFx is […]

BeansBinding Performance (Issue 37)


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Reading the contents of a file in Java is a very straightforward operation. The java tutorial explains completely how you can find your way to read different types of streams. However when you read an UTF-8 encoded file your fight will start. Most of the UTF-8 and UTF-16 encoded files contain a character at the beginning called BOM (byte-order mark). The BOM consists of a character  (U+FEFF) at the beginning of the stream used to define the byte order and the encoding of the stream. UTF encoded files may or may not contain the BOM. The problem with Java comes when […]

Reading UTF-8 encoded documents in java



Linksys WVC200 11
So you bought an IP camera and would like to store/see images from the camera using java. Recently I bought a couple of IP Cameras for testing purposes. I noticed that each IP camera has different surveillance tools and web interfaces. But most of them have in common that you can access the actual picture by entering an url in your browser. In this post I’ll show you how to see that image and store it using a very simple jav application. The camera I’ll use for the test is a LinkSys WVC200 “Wireless PTZ Internet Camera with Audio”. This […]

Viewing and storing images from an IP Camera


In many cases, web applications give OutOfMemoryError when their threads require high levels of  memory. Image manipulation or intensive database use or calculation can lead to this very common problem. Normally when you get an OutOfMemory error in a desktop application, you can solve this problem by specifying the java commands -Xms*** (initial Java heap size) and -Xmx*** (maximum Java heap size) when running your program. To solve this issue in tomcat, you must specify these options in the tomcat startup command / script / batch. In windows tomcat is installed as a service. Tomcat provides a configuration tool to […]

java.lang.OutOfMemoryError: PermGen space // More memory for Tomcat under windows