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Create and test a simple Linux app
Tom Mitchell (tommitch@us.ibm.com), WebSphere Technical Sales Support Team, IBM
Ian Shields (ishields@us.ibm.com), Senior programmer, IBM
01 Jan 2002
Updated 25 Mar 2003 This article shows you how to create and test a "Hello, World" application using WebSphere Studio Site Developer in a Linux environment, and then shows you how to add a "scrap page" for testing snippets of Java code. This article was originally published in January 2002 using examples from a Windows environment. Tom Mitchell developed the original article, and Ian Shields added the Linux updates for WebSphere Studio Site Developer V5 that you see here.
Introduction
When evaluating development tools, it is common to focus on
features that simplify, accelerate, or make practical the development of complex
applications. One of the underlying fundamentals of all IBM tools is the promise
of making development of complex components easier and faster. WebSphere® Studio
Site Developer (Site Developer) has a rich set of features
that deliver on this promise. These features greatly simplify and accelerate
the process of developing, testing, and deploying complex J2EE applications
containing HTML, JSPs™, Servlets, Java™ beans, and other components.
Development tools should take into account the fact that
many of the day-to-day tasks that a developer performs
are fairly simple and narrow in scope. A good tool must allow simple tasks to
remain simple. Frequently, Java developers create a small application to test
or experiment with a simple Java feature. In these cases, development tools
should help the developer to quickly create, build, and test the application.
They shouldn't require the developer to navigate through or even be aware of
the more advanced features and project structuring that would be needed to
create large, complex J2EE applications.
One of the first things I do when evaluating a new tool is
to create the classic (or cliché, depending on your opinion) "Hello, World"
application. Once that works, I feel I have a solid base from which I can experiment
with the other features. Ideally, I like to be able to perform this task without
any product education. In fact, I've been known to skip the product documentation
altogether. I imagine there are a few other "try it first, read the documentation
later" types out there as well. As you will see, the "Hello, World"
exercise is very easy and intuitive with Site Developer.
The rest of this article shows you how to create and test
a "Hello, World" application, and then shows you how easy it is to
add a "scrap page" for testing snippets of Java code. Site Developer is well suited
to both simple and complex development tasks.
Two minutes or less to a "Hello, World" application
The steps below assume you are using the 60-day trial edition of Site Developer.
Let's review the user interface first. Site Developer is a task-oriented tool whose user
interfaces are customized for the task being performed. The interface used for
developing a JSP is much different from the one for Server development. Application
Developer lets you control what windows and views you see by switching the
perspective you are using. A perspective is a set of views that show the
resources you need when performing a specific task. Site Developer has
perspectives defined for Web application development, J2EE development, debugging,
and many other common tasks.
The left navigation bar contains icons that
allow you to easily switch between perspectives. We will skip the Welcome
panel that tells us how to use the IDE as we can always come back to it later
using Help=>Welcome.
- Start Site Developer and open a Java perspective. To open Site
Developer, run /usr/bin/wssitedev50 from a terminal
window or just wssitedev50 if
/usr/bin is in your
path as it usually is. You can also do this from the taskbar on your
desktop. For example, with KDE select Start Application=>Run Command...
and type in wssitedev50 or
/usr/bin/wssitedev50 as appropriate.
Next, select Window=>Open perspective => Java from the main menu.
Figure 1. Opening a Java perspective
- Alternatively, you can click the Open Perspective button and select
Java from the submenu.
Figure 2. Using the Open Perspective tool
- Next, create a new Java project. Select File => New => Project
or use the New Wizard button at the left end of the toolbar above the Open Perspective button. On the New Project dialog, select Java in the left column and Java
Project in the right column.
Figure 3. Creating a new Java project
- Click Next and enter the project name Hello in the project name field.
Then click Finish to create the project.
- Now you will see the Hello project in the Packages view.
Figure 4. The Hello project in the Packages view
- Add the Hello class. To do this, right-click on the Hello package
and select New => Class, or simply click on the New Class
button in the toolbar while the Hello package is selected.
Figure 5. Creating a new class
- Type Hello in the name field and check the option to create a
public
static void main(String[] args) method.
Figure 6. Creating the Hello class
- Click Finish and the main window
should look this:
Figure 7. The Hello class
- You could now run the application, but it wouldn't do anything, so we'll
add one line of code to the main method. After the left brace ({),
add
System.out.println("Hello, World");
- You can add code like this more quickly by using code-assist. After you've
typed
System, key Ctrl-space, and a code-completion
dialog will present valid object/method names. Code-assist reduces both keystrokes
and errors significantly.
Figure 8. Using code-assist to add code
- Type Ctrl-S
(or use File=>Save) to save and compile the Hello class.
- Click the Run button to start the application
 .
If this is the first time you've done this, a dialog will ask how
the application should be launched. Select Java Application and
click New.
Figure 9. Creating a configuration
- On the next screen you can specify arguments for your application and additional information such as the JRE to use.
For now, just click Apply and then click Run.
Figure 10. Specifying configuration details
- Your application will run, and you will see your
output in the console window:
Figure 11. Running the application
- As you can see, Site Developer helps you get started quickly and
simply. I timed myself when verifying the steps and it took 71 seconds.
- While it's unlikely that you'd need a debugger to follow the flow of this
application, it's very easy to add breakpoints and debug. To set a breakpoint,
right-click in the gray bar to the left of a line of code and select
Add Breakpoint. Once you've set a breakpoint, a green circle
appears in the gray bar to the left of the line of code.
Figure 12. Setting a breakpoint
- To debug, click the Debug button, not the Run button. Clicking
Run causes the application to run without stopping at the breakpoints.
A debug perspective will open and you will see the debug perspective icon on
the left side of your screen. Use the Run menu to see your choices, including
the usual items such as Step into, Step over, Resume, and so on.
For now, press F6 to step over our line of code and notice the output appear in
the lower console window. Press F8 to complete execution.
Figure 13. The debug perspective
- When you have finished, right-click on the debug perspective icon to close the debug perspective.
Alternatively, you may click on Window=>Close perspective.
Want more speed?
So far, you've seen a fastpath for running and debugging applications.
For testing a few lines of code, there's an even quicker path: the
scrapbook page.
- To see it in action, take your "Hello, World" project. If you are not already viewing the Java perspective, click the navigation button on the left to return to the Java perspective.
- Now select the Hello project, then
right-click on it
and select New => Scrapbook page.
Figure 14. Creating a scrapbook page
- Enter Scrap for the scrapbook file name and click Finish. You will
return to the Java perspective with the
Scrap.jpage
file open.
Figure 15. Scrap.jpage in the Java perspective
- Now type the same line of code in that we used before:
System.out.println("Hello,
World"). You can still use code-assist to complete method names.
Select the line of code, right-click on it, and select Run snippet. The line
of code will be compiled and executed. You don't need a main, or any other
method definition, to test it.
Figure 16. Entering a code snippet
- After the code runs, you will see the result in the console pane at the bottom of the Site Developer window:
Figure 17. Running a code snippet
- The asterisk in front of the
scrap.jpage
tab indicates that you have not yet saved the file. Select Ctrl-S to
save it, and the asterisk will disappear.
That is all there is to it! "Hello World" in under
two minutes.
Summary
While WebSphere Studio Site Developer is a great tool
for developing complex, multi-tier J2EE applications, it also excels at quick
development of simple applications. With its unique task-oriented interface and
its ability to switch perspectives, it is the tool of choice for all kinds of
development tasks. Give it a try and you'll soon be on your way to increased
productivity.
Resources About the authors
Tom Mitchell is an application architect with the WebSphere Technical Sales Support team at IBM. He spends most of his time helping
customers understand the WebSphere family of products, how it implements the
J2EE specifications, and where it is going in the future. He is a co-author
of Professional Java Fundamentals (WROX Press, 1996). It is a "must have" for
people still developing AWT applications for Java 1.0. You can contact Tom at
tommitch@us.ibm.com. |
Currently researching Linux technology for the developerWorks Linux zone, Ian Shields is a Senior Programmer at IBM at the Research Triangle Park, NC. He joined IBM in Canberra, Australia, as a systems engineer in 1973, and has since worked on communications systems and pervasive computing in Montreal, Canada, and RTP, NC. He has several patent filings and seven issued patents. His undergraduate degree is in pure mathematics and philosophy from the Australian National University. He received an M.S. in computer science from North Carolina State University, where he is now pursuing a Ph.D. You can contact Ian at ishields@us.ibm.com.
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