1. CS288
Lab Exercise 1

2. Open PersonGui Files Go to Course web site for PersonGui source files
Make copies of these files in you home folder and then open
them in some editor (e.g. Emacs):
PersonGui.java
PersonMaker.java
Person.java
images.zip (unzip this file in the same directory as you have put the java files)
Download a copy of these slides so that you can read them directly, and not simply view them in Internet Explorer. This is handy as you can then copy and paste code examples directly from these slides.

3. Read the slides on compiling Java Code
Make sure you have read the notes on compiling Java Code:
Compile PersonGui.java. In a command window type:
javac PersonGui.java
now run the application
java PersonGui
Right click the mouse in the large text area.
You should see a popup menu.
Enter in your name age height etc with this menu.
Right click the mouse and choose the create person item.
If you have installed the images correctly from the zip file you should be
able to choose a suitable image at this point.

4. How the PersonGui should appear
Choose this option
should cause this
dialog to appear

5. How the PersonGui should appear
Once you have picked an image it should then appear as
below.

6. 1: Search for Make_Person method
Find (could use Search in Emacs) the Make_Person ( )
method in PersonMaker.java

7. 1: Change the Make_Person method
Change the value of Make_Person to this:
public String Make_Person ( ) {
Show_Attributes_InFrame ();
String return_value =
"This Person has these attributes: \n " +
"\n\tFirst Name \t= " + getFirstName() +
"\n\tLast Name \t= " + getLastName() +
"\n\tHeight \t= " + getPersonHeight() +
"\n\tAge \t= " + getPersonAge() + "\n";
return return_value; }
Delete any .class files you have. Recompile and rerun the code.
This should not make any difference to the way the code works.
Test your code to make sure that is true.

8. 1: Change the Make_Person method again
Change the value of Make_Person to this:
public String Make_Person ( ) {
Show_Attributes_InFrame ();
String return_value =
"This Person has these FANTASTIC attributes: \n " +
"\n\tFirst Wonderful Name \t= " + getFirstName() +
"\n\tLast Stunning Name \t= " + getLastName() +
"\n\tLook at that Height \t= " + getPersonHeight() +
"\n\tLook at that Age \t= " + getPersonAge() + "\n";
return return_value; }
Recompile and rerun the code.
How does this change the way the code works?

9. 1: Change the Make_Person method again
Change the value of Make_Person to this:
public String Make_Person ( ) {
Show_Attributes_InFrame ();
String the_empty_string = ""; //This will be handy for the next part
String return_value =
"This Person has these FANTASTIC attributes: \n ";
return_value = return_value +
"\n\tFirst Wonderful Name \t= " + getFirstName();
"\n\tLast Stunning Name \t= " + getLastName();
"\n\tLook at that Height \t= " + getPersonHeight();
"\n\tLook at that Age \t= " + getPersonAge() + "\n";
return return_value; }
Recompile and rerun the code.
How does this change the way the code works?

10. 1: Set Empty String as Age
If we set the first name to be empty with the menu:

11. 1: Empty String as Age
Then we get a somewhat redundant message on the screen

12. 1: Look in PersonGui.java
Change the Make_Person method so that if the user enters a value for Age that is the empty string, then the Make_Person returns a String that says:
You entered an empty string for the first name
Instead of
The Persons First Name is: ""
If the user enters a non-empty string the return value is unchanged.
To do this you need to use an if statement. See the Java Tutorial on the course web site to see how if statements work:
Go to the section on Learning the Java Language then to Language Basics
then to Expressions, Statements, and Blocks
Also you need to understand how some of the methods work for the String class.
Go to the Java SDK 2, Class Specifications link on the course web site:

13. Search for
the String class in
this column.
Click on the String
link

14. Then click on
the METHOD link
at the top of the
page.
Now find the
equals method
for this class.
This is useful if
you want to know
if a string is the
empty string.

15. 1: Change the Make_Person method again
Now change the Make_Person method again so that if the User enters an
empty string for the last name of someone a more sensible string is returned.
Now change the method so that if a users age is greater than then
the return_string makes a suitable comment about how incredibly old that
person is.

16. 2: Find PersonMaker Constructor
Find the PersonMaker constructor in the PersonMaker.java
file
Find the reset_Person ( ) method.

17. 2: PersonMaker
Note the contents of reset_Person ( ) and PersonMaker ( )
are the same.
Define a third method,
public void set_default_values ( )
which is just a copy of the current reset_Person method with
new name.
Now change reset_Person ( ) and PersonMaker ( )
so that they simply call the set_default_values ( ) method
and do not change any variable directly themselves.

18. 3: Removing Redundant Labels
Find the Person constructor method in the Person.java file

19. 3: Removing Redundant Labels
Person ( ) creates a seperate JLabel for height, age, first
and last names. This is redundant. Change the code so
that Person ( ) only uses one JLabel for all the strings that
are to be displayed.
The purpose of this exercise is for you to learn how to track
all the data that is associated with one variable, and also
modify that data for a different purpose.

20. 3: Removing Redundant Labels
For example in this case, you will have to work out where
variables
first_text
last_text
age_text
height_text
are referred to in the rest of the method.
You will have to figure out how to combine these variables into a single string (new String variable declaration).
You will have to comment out those parts of the code that set up and use unwanted JLabels (such as label_first).
You will have to create a new JLabel for the combined text.
Now attach the JLabel somehow so that it replaces the four redundant labels.
You will be able to do this simply by copying the way the other JLabels are defined, you dont need to understand what it all means yet.