Due December 8th, at noon
1/3
Tutorial 8
F21 – COMP1006/1406 – Introduction to Computer Science II
Objectives
Use a Java package. Complete either Tutorial 6 or 7.
Notes
Exercise 1 is asking you compile files that are in a Java package and then run a program in that
package.
Exercise 2 is asking you to complete either Tutorial 6 or 7 (whichever you did not do last time).
QUESTION 1
Taken from the Oracle tutorial pages
(https:
docs.oracle.com/javase/tutorial/java/package/packages.html)
To make types easier to find and use, to avoid naming conflicts, and to control access,
programmers bundle groups of related types into packages.
A package is a grouping of related types (which include classes, interfaces, enumerations
and annotation types) providing access protection and namespace management.
The types that are part of the Java platform are members of various packages that bundle
classes by their function. For example, fundamental classes are in java.lang, classes for
eading and writing (input and output) are in java.io, and so on. You can make your own
packages too.
Why collect the classes and interfaces into a package?
• You and other programmers can easily determine that these types are related.
• The names of your types won't conflict with the type names in other packages
ecause the package creates a new namespace.
• You can allow types within the package to have unrestricted access to one another
yet still restrict access for types outside the package.
https:
docs.oracle.com/javase/tutorial/java/package/packages.html
Due December 8th, at noon
2/3
The default access modifier (i.e., the absence of an access modifier) specifies that any other
type within the package can access it. It is sometimes refe
ed to as package-private access.
When using a package, call it ourPackage, all files must be in a directory (folder) with the
same name (ourPackage). Each file must also have the package directive at the top of the
file:
package packageName;
Now, an issue that many face when using packages is that compiling and running is done
slightly different. In this exercise, you will be using a command prompt (windows cmd or
mac Terminal) to manually compile and run code from a package.
Download the tutotial08.zip file and unzip its contents. You will find a directory called
tutotial08 and several files inside it. Notice that each file has package tutorial08; as its first
line.
Compiling: Go to the directory that has the tutotial08 folder in it. Do not go into the
tutotial08 directory though. Compile all the java files in the tutorial08 directory with the
following command based on your OS.
Using windows: XXXXXXXXXXjavac tutorial08\*.java
Using a Mac or Linux: XXXXXXXXXXjavac tutorial08/*.java
This will compile all the files in the folder. You could have moved into the directory and
directly compiled the files from there (like you would have done in previous tutorials), but
to be consistent with running a program, it is best to compile from the same directory that
contains the directory with the package contents.
Running: To run the Tut08 program, from the directory that has the tutorial08 directory,
invoke the JVM with the following command
java tutorial08.Tut08
Notice that the [back]slash is replaced with a dot. This will run the tut08 program.
Try to compile and run the UsePackage.java program. This program is NOT part of the
tutorial08 package, but it uses one of its classes.
Due December 8th, at noon
3/3
QUESTION 2
You had the option of either completing Tutorial 7 or the optional Tutorial 6. Complete
whichever one you did NOT do and submit the files here in the Tutorial 8 submission link.