Java Reference
In-Depth Information
2.
If necessary, display the contents of MyFirstProject and myFirstPackage by clicking their
expansion icons in the Project Explorer view.
Notice that the navigation tree shows the file names of the two Java classes created so far.
3.
If necessary, in the navigation tree, double click Employee.java to display the source code
in the content pane.
The tab at the top of the content pane will show the file name along with the RAD icon that represents a Java
source code file (a white sheet of paper with a blue J).
In the navigation tree, notice that there is another item within MyFirstProject called “JRE System Library”. When
the project was created, RAD made sure all the classes in the project had access to a JRE. As a matter of fact, RAD
contains a full JDK. (In the case of the Enterprise Edition, there is a JEE JDK). You never had to worry about a JDK,
JVM, or JRE because they came prepackaged. (Wasn't that nice of RAD?) These software items are further examples
of what was meant by “development tools” in Chapter 1 when we said “WebSphere is an IBM software product that
includes all the 'development tools' a programmer would need to write, debug, and install application software.”
4.
Click on the JRE System Library expansion icon.
The displayed item's text is too long to fit in the Package Explorer pane. Move the cursor over an item to display
the full text in a pop-up box. Alternatively, the RAD panes can be resized. Simply move the cursor over the border of
the pane, click, and drag.
5.
Move the cursor over the right border of the Package Explorer pane.
When the cursor is over a border, the mouse cursor icon will change from a white, single headed arrow to a white,
double-headed, horizontal, arrow.
6.
Click and drag the Package Explorer pane's right border so that all the text for each item
can be seen (see Figure
2-15
).
Figure 2-15.
The new items are “jar” (
j
ava
ar
chive) files. A jar file holds java resources but uses less space. (A “jar” file is
actually a specialized “zip” file.) These jar files hold the packages that contain the Java classes (like
String
) that
“come with Java.”
7.
Expand the vm.jar file (listed under the JRE System Library).
The package names within vm.jar are listed in alphabetical order and often contain the name of the organization
supplying the package or class. Notice that the first several packages are from IBM.
