Welcome!

Eclipse Authors: Elizabeth White, Liz McMillan, XebiaLabs Blog, Ken Fogel, Sematext Blog

Related Topics: Eclipse, Java IoT, Open Source Cloud

Eclipse: Article

How to Bring Eclipse 3.1, J2SE 5.0, and Tomcat 5.0 Together

How to create a Web project that has Java classes located in different packages and how we use ANT

Eclipse is the most popular Open Source IDE on the Java market and the latest 3.1 release supports all the new language elements of J2SE 5.0.

In this article I'll show you see how to create a Web project that has Java classes located in different packages and how to use ANT to build this project and JUnit to test it. I assume that you have J2SE 5.0 installed and are familiar with Ant and JUnit.

Building Java 5.0 Applications with Eclipse
We'll build a servlet that will demo some new Java 5.0 features and do some basic tasks like creating a session to track user visits to multiple Web pages. This code can easily be extended to store a user ID in the session that will travel with her as the site is navigated. The value of the visit counter is stored in the session so multiple visits to the page will be counted (this includes the page refreshes after pressing the browser's "Reload" button). If the counter goes over five, the counter gets cleared.

Installing Tomcat
I've used Tomcat 5.0, which is available at http://jakarta.apache.org/tomcat/. Installation is a breeze, and it's smart enough to find your installation of J2SE 5.0. It also lets you test Java servlets easily on your own machine. Other that making you restart the server every time a new servlet is deployed, Tomcat is a great server for what we're doing and many other tasks.

Creating a New Project in Eclipse
To create our servlet, start by creating a new Java project by selecting the menus File, New, and Other. Then specify the name of the project, say, MyJavaProject, (make sure that J2SE 5.0 is selected as the default JRE), and click Finish. Actually, Eclipse lets you select a different version of the Java runtime at any time using the menus Windows, Preferences, Java > Installed JRE's. You can also set the compiler compliance level on the project level by selecting Java Compiler under the project's properties.

Since the standard J2SE 5.0 SDK doesn't support servlets, let's add the servlet.jar that comes with Tomcat. It's in its directory common\lib\servlet-api.jar. To add this external jar to an Eclipse project, right-click on MyJavaProject, select properties, Java Build Path, and under the Libraries tab add this external jar. Now our servlets will compile.

Eclipse by itself doesn't support debugging with Tomcat unless you add some custom Web development plug-ins to it, such as Web Tools Project (WTP). It's possible to debug Tomcat applications using Eclipse remote debugging capabilities. For more information see the Java Developer's Journal at http://java.sys-con.com/read/44918.htm.

Some of the New J2SE 5.0 Features
Let's create several supporting classes that will be used by our servlet and demonstrate some of the J2SE 5.0 capabilities. It's always a good idea to keep classes in separate packages based on functionality or some other criteria. Let's call the package "support." Just right-click on the project name, select "New Package," and enter the package name.

Autoboxing
Create a new class called Boxer that will support Java 5.0 enhanced boxing and unboxing operations. Right-click on the Java project, and select a New Class (un-check creation of the main method). Enter the source code of the class as shown in Listing 1 at the end of the article.

Just press Ctrl-S and the class is saved and compiled. As you can see, it has three methods for boxing, unboxing, and simplified adding to a collection.

Generics
Now create another class called Generic that shows how to eliminate the need for casting when retrieving elements from a collection by introducing generic collection types. You can specify the type of collection elements during its creation (see Listing 2). Generic types let objects of the same class operate safely on objects of different types. For example, they provide compile-time assurances that a List<String> always contains Strings and a List<Integer> always contains Integers.

Eclipse can handle both generic and non-generic types:

  • Generic types can be safely renamed.
  • Type variables can be safely renamed.
  • Generic methods can be safely extracted from or inlined into generic code.
  • Code assist can automatically insert appropriate type parameters in parameterized types.
In addition, a new refactoring option has been added. "Infer Generic Type Arguments" can infer type parameters for every type reference in a class, a package, or an entire project.

Enhanced For Loop
The next useful feature of J2SE 5.0 provides support for the enhanced "for" loop. This spares us from creating an iterator, navigating it, and retrieving elements from it. Create this class in Eclipse in the same package support (see Listing 3).

Java printf Function
Now, C-lovers, you can use the printf function in Java so create one more class as in Listing 4.

Methods with Variable Number of Arguments (varargs)
Java 5.0 lets you create methods with a variable number of arguments as in Listing 5. This method's signature is pretty similar to the public static String[] format(String str, Object[] args), however, it's more elegant to invoke since multiple arguments can be just passed on the command line rather than having to construct a whole new array.

Don't forget to create this class in the package support.

Static Imports
Allows importing static constants and methods, saves on extra mentioning of static classes (see Listing 6).

Creating a Servlet
Now that we've created all the supporting classes, let's create a servlet. First, we create a new package called servlet in our project.

Then, we can just create a SampleServlet class by selecting HttpServlet as a superclass in the Eclipse class creation window.

Servlets can handle all the HTTP protocol invocation types. GET and POST are the most common ones, through. Servlet code is in Listing 7.

More Stories By Boris Minkin

Boris Minkin is a Senior Technical Architect of a major financial corporation. He has more than 15 years of experience working in various areas of information technology and financial services. Boris is currently pursuing his Masters degree at Stevens Institute of Technology, New Jersey. His professional interests are in the Internet technology, service-oriented architecture, enterprise application architecture, multi-platform distributed applications, and relational database design. You can contact Boris at [email protected]

Comments (13) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
sumeet jaju 07/28/06 07:40:26 AM EDT

Thanks for you

SYS-CON Belgium News Desk 01/07/06 02:16:35 PM EST

We'll build a servlet that will demo some new Java 5.0 features and do some basic tasks like creating a session to track user visits to multiple Web pages. This code can easily be extended to store a user ID in the session that will travel with her as the site is navigated. The value of the visit counter is stored in the session so multiple visits to the page will be counted (this includes the page refreshes after pressing the browser's 'Reload' button). If the counter goes over five, the counter gets cleared.

SYS-CON Australia News Desk 01/06/06 12:59:13 PM EST

We'll build a servlet that will demo some new Java 5.0 features and do some basic tasks like creating a session to track user visits to multiple Web pages. This code can easily be extended to store a user ID in the session that will travel with her as the site is navigated. The value of the visit counter is stored in the session so multiple visits to the page will be counted (this includes the page refreshes after pressing the browser's 'Reload' button). If the counter goes over five, the counter gets cleared.

Lester D'Souza 01/06/06 12:24:47 PM EST

A great article. I had to struggle to get it working due to some errors and typos. I wish I could upload my entire Eclipse project as part of the feedback. The nice thing about this set up was that I could modify my Servlet, then using the create-war, undeploy and deploy my changes on the tomcat server with the click of a button. Tomcat would detect my changes, and when I refreshed the browser, I could see my changes. This is an ideal setup for any web based development. Also I would like to mention that this is my first experience with Eclipse, Tomcat and Ant. I would like to rewrite this article and leave out the J2SE 5.0 stuff, since it does not fit in very well. Also I was able to use Junit to test the code.

Eclipse News Desk 01/05/06 08:31:49 PM EST

We'll build a servlet that will demo some new Java 5.0 features and do some basic tasks like creating a session to track user visits to multiple Web pages. This code can easily be extended to store a user ID in the session that will travel with her as the site is navigated. The value of the visit counter is stored in the session so multiple visits to the page will be counted (this includes the page refreshes after pressing the browser's 'Reload' button). If the counter goes over five, the counter gets cleared.

SYS-CON Australia News Desk 01/05/06 07:38:14 PM EST

We'll build a servlet that will demo some new Java 5.0 features and do some basic tasks like creating a session to track user visits to multiple Web pages. This code can easily be extended to store a user ID in the session that will travel with her as the site is navigated. The value of the visit counter is stored in the session so multiple visits to the page will be counted (this includes the page refreshes after pressing the browser's 'Reload' button). If the counter goes over five, the counter gets cleared.

Carrie Latimer 01/05/06 07:01:44 PM EST

I ran into the same issues Eric ran into. Help please. Thank you and take care.

Carrie Latimer 01/05/06 07:01:34 PM EST

I ran into the same issues Eric ran into. Help please. Thank you and take care.

Eric Bresie 11/16/05 09:02:26 AM EST

I was reading your article about Eclipse and Tomcat and was trying to follow on and ran into a snag or two.

One problem that I did find was that the SampleProgram has a class name in the file of TestProgram.

The other problem, and I'm not sure if this may not be an Eclipse project setup issue, environment issues, or something else, but when I try to compile the SampleProgram and reference the ForLoop's convertToString, it indicates that it cannot be resolved. I believe I have the classes included into the project correctly, so I am still a little confused.

Since this is my first encounter with Java 5's new features such as the new forloops, I am not as familiar with this and was hoping you might have some idea.

Do you have any ideas? Have you encountered a similar problem?

Thanks ahead of time.

Eric Bresie
[email protected]

Servlet Newbie 11/10/05 12:22:30 PM EST

Very good article!

...however: I cannot seem to get the servlet running. I can see that it is deployed, but if I type http://localhost:8080/myapp/SampleServlet/
it gives me a required resource not found...

Help please

Eugenio Leal 11/01/05 07:47:57 PM EST

Eclipse sucks. Websphere sucks. Netbeans Rules.

Bernie's ramblings... 10/20/05 04:46:38 AM EDT

Trackback Added: Eclipse, J2SE5 and Tomcat; I’ve always liked to read about Eclipse, and knowing more about it has often made me able to work better. There’s always just some gurus out there that seems to be able to make programming a bit more bearable. An article I came across today...

Enterprise Open Source Magazine News Desk 10/17/05 03:31:03 PM EDT

Enterprise Open Source Magazine - How to Bring Eclipse 3.1, J2SE 5.0, and Tomcat 5.0 Together
We'll build a servlet that will demo some new Java 5.0 features and do some basic tasks like creating a session to track user visits to multiple Web pages. This code can easily be extended to store a user ID in the session that will travel with her as the site is navigated. The value of the visit counter is stored in the session so multiple visits to the page will be counted (this includes the page refreshes after pressing the browser's 'Reload' button). If the counter goes over five, the counter gets cleared.

@ThingsExpo Stories
In his session at @ThingsExpo, Chris Klein, CEO and Co-founder of Rachio, will discuss next generation communities that are using IoT to create more sustainable, intelligent communities. One example is Sterling Ranch, a 10,000 home development that – with the help of Siemens – will integrate IoT technology into the community to provide residents with energy and water savings as well as intelligent security. Everything from stop lights to sprinkler systems to building infrastructures will run ef...
SYS-CON Events announced today that Peak 10, Inc., a national IT infrastructure and cloud services provider, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Peak 10 provides reliable, tailored data center and network services, cloud and managed services. Its solutions are designed to scale and adapt to customers’ changing business needs, enabling them to lower costs, improve performance and focus inter...
You think you know what’s in your data. But do you? Most organizations are now aware of the business intelligence represented by their data. Data science stands to take this to a level you never thought of – literally. The techniques of data science, when used with the capabilities of Big Data technologies, can make connections you had not yet imagined, helping you discover new insights and ask new questions of your data. In his session at @ThingsExpo, Sarbjit Sarkaria, data science team lead ...
Artificial Intelligence has the potential to massively disrupt IoT. In his session at 18th Cloud Expo, AJ Abdallat, CEO of Beyond AI, will discuss what the five main drivers are in Artificial Intelligence that could shape the future of the Internet of Things. AJ Abdallat is CEO of Beyond AI. He has over 20 years of management experience in the fields of artificial intelligence, sensors, instruments, devices and software for telecommunications, life sciences, environmental monitoring, process...
Increasing IoT connectivity is forcing enterprises to find elegant solutions to organize and visualize all incoming data from these connected devices with re-configurable dashboard widgets to effectively allow rapid decision-making for everything from immediate actions in tactical situations to strategic analysis and reporting. In his session at 18th Cloud Expo, Shikhir Singh, Senior Developer Relations Manager at Sencha, will discuss how to create HTML5 dashboards that interact with IoT devic...
So, you bought into the current machine learning craze and went on to collect millions/billions of records from this promising new data source. Now, what do you do with them? Too often, the abundance of data quickly turns into an abundance of problems. How do you extract that "magic essence" from your data without falling into the common pitfalls? In her session at @ThingsExpo, Natalia Ponomareva, Software Engineer at Google, will provide tips on how to be successful in large scale machine lear...
The IoTs will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, will demonstrate how to move beyond today's coding paradigm and share the must-have mindsets for removing complexity from the development proc...
SYS-CON Events announced today that Ericsson has been named “Gold Sponsor” of SYS-CON's @ThingsExpo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. Ericsson is a world leader in the rapidly changing environment of communications technology – providing equipment, software and services to enable transformation through mobility. Some 40 percent of global mobile traffic runs through networks we have supplied. More than 1 billion subscribers around the world re...
You deployed your app with the Bluemix PaaS and it's gaining some serious traction, so it's time to make some tweaks. Did you design your application in a way that it can scale in the cloud? Were you even thinking about the cloud when you built the app? If not, chances are your app is going to break. Check out this webcast to learn various techniques for designing applications that will scale successfully in Bluemix, for the confidence you need to take your apps to the next level and beyond.
There is an ever-growing explosion of new devices that are connected to the Internet using “cloud” solutions. This rapid growth is creating a massive new demand for efficient access to data. And it’s not just about connecting to that data anymore. This new demand is bringing new issues and challenges and it is important for companies to scale for the coming growth. And with that scaling comes the need for greater security, gathering and data analysis, storage, connectivity and, of course, the...
SYS-CON Events announced today that Fusion, a leading provider of cloud services, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Fusion, a leading provider of integrated cloud solutions to small, medium and large businesses, is the industry's single source for the cloud. Fusion's advanced, proprietary cloud service platform enables the integration of leading edge solutions in the cloud, including cloud...
Digital payments using wearable devices such as smart watches, fitness trackers, and payment wristbands are an increasing area of focus for industry participants, and consumer acceptance from early trials and deployments has encouraged some of the biggest names in technology and banking to continue their push to drive growth in this nascent market. Wearable payment systems may utilize near field communication (NFC), radio frequency identification (RFID), or quick response (QR) codes and barcodes...
The increasing popularity of the Internet of Things necessitates that our physical and cognitive relationship with wearable technology will change rapidly in the near future. This advent means logging has become a thing of the past. Before, it was on us to track our own data, but now that data is automatically available. What does this mean for mHealth and the "connected" body? In her session at @ThingsExpo, Lisa Calkins, CEO and co-founder of Amadeus Consulting, will discuss the impact of wea...
SYS-CON Events announced today that DatacenterDynamics has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY. DatacenterDynamics is a brand of DCD Group, a global B2B media and publishing company that develops products to help senior professionals in the world's most ICT dependent organizations make risk-based infrastructure and capacity decisions.
The IoT has the potential to create a renaissance of manufacturing in the US and elsewhere. In his session at 18th Cloud Expo, Florent Solt, CTO and chief architect of Netvibes, will discuss how the expected exponential increase in the amount of data that will be processed, transported, stored, and accessed means there will be a huge demand for smart technologies to deliver it. Florent Solt is the CTO and chief architect of Netvibes. Prior to joining Netvibes in 2007, he co-founded Rift Technol...
We’ve worked with dozens of early adopters across numerous industries and will debunk common misperceptions, which starts with understanding that many of the connected products we’ll use over the next 5 years are already products, they’re just not yet connected. With an IoT product, time-in-market provides much more essential feedback than ever before. Innovation comes from what you do with the data that the connected product provides in order to enhance the customer experience and optimize busi...
SYS-CON Events announced today that Stratoscale, the software company developing the next generation data center operating system, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Stratoscale is revolutionizing the data center with a zero-to-cloud-in-minutes solution. With Stratoscale’s hardware-agnostic, Software Defined Data Center (SDDC) solution to store everything, run anything and scale everywhere...
Angular 2 is a complete re-write of the popular framework AngularJS. Programming in Angular 2 is greatly simplified – now it's a component-based well-performing framework. This immersive one-day workshop at 18th Cloud Expo, led by Yakov Fain, a Java Champion and a co-founder of the IT consultancy Farata Systems and the product company SuranceBay, will provide you with everything you wanted to know about Angular 2.
SYS-CON Events announced today that Men & Mice, the leading global provider of DNS, DHCP and IP address management overlay solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. The Men & Mice Suite overlay solution is already known for its powerful application in heterogeneous operating environments, enabling enterprises to scale without fuss. Building on a solid range of diverse platform support,...
Whether your IoT service is connecting cars, homes, appliances, wearable, cameras or other devices, one question hangs in the balance – how do you actually make money from this service? The ability to turn your IoT service into profit requires the ability to create a monetization strategy that is flexible, scalable and working for you in real-time. It must be a transparent, smoothly implemented strategy that all stakeholders – from customers to the board – will be able to understand and comprehe...