Java Reference
In-Depth Information
Every Java application has only one
main
method.
Note
You use the
javac
program in the
bin
directory of your JDK installation directory to compile Java
programs. Assuming you have edited the PATH environment variable on your computer, you should
be able to invoke
javac
from any directory. To compile the
HelloWorld
class in Listing 1-1, do the
following:
1.
Open a command prompt and change to the directory where the
HelloWorld.
java
file is saved.
2.
Type the following command:
javac HelloWorld.java
If everything goes well,
javac
will create a file named
HelloWorld.class
in your working directory.
Running Your Java Application
To run your Java application, you have to use the
java
program that is part of the JDK with the
command
java <class name>
. Again, having added the PATH environment variable, you should be
able to invoke
java
from any directory. From your working directory, type the following:
java HelloWorld
Note that you do not include the
.class
extension when running a Java application. You will see the
following on your console:
Hello World.
Developing Java Applications with an IDE
In this topic you will use the Eclipse
Kepler
integrated development environment (IDE). To download
it, follow these steps:
1.
2.
Follow the instructions provided by the web site.
3.
Run the installer and accept any defaults.
Creating Your First Project in the IDE
After you've started Eclipse, you can make a new project as follows:
1.
From the File menu, select New, and then select Project. The New Project
window appears.
2.
In the New Project window, double-click Java Project. The New Java Project
window appears, as illustrated in Figure
1-7
.
