EBU4201 Introductory Java Programming 2022/23
Task 1 [30 marks]
SumItUp is a simple application for children where they can practise their counting and adding
skills (see Figure 1).
Figure 1 First launch with some input values entered
A random number of Rabbit images ranging from 1 to 10 are displayed for each operand and the
user is expected to enter the values of the two operands and the result of adding the two operands,
in the given text fields. When the user clicks on the button ‘Check!’, one of two things can happen:
Case 1: all three input values are correct
i) the text changes to ‘"Correct! Have another go?"’.
ii) the number of Rabbit images displayed for each of the two operands changes. See Figure
2 for an example.
iii) the three text fields are reset (i.e. they are made empty).
Case 2: at least one of the input values entered is incorrect
i) the text changes to ‘Wrong! Try again!’.
ii) the number of Rabbit images displayed does NOT change.
iii) the text fields do NOT change.
Figure 2 Action following Case 1
Implement SumItUp as a Java application. You application must satisfy ALL the specific
requirements given below:
a) The title of the top-level container must be ‘Welcome to SumItUp!’.
b) The initial text should be ‘Enter two operands, result and click on 'Check!'’. See Figure
c) There should be no more than 4 Rabbit images per row. See Hint 1.
d) The text fields should be wide enough to display at least TWO characters.
e) The button ‘Check!’ must not resize when the GUI is resized. See Hint 2 and Figure
f) The ‘plus sign’ icon should appear vertically centered between the two sets of Rabbit
images and must not resize when the GUI is resized. See Hint 2 and Figure 3.
g) When first launched and whenever a correct answer is given, the number of displayed
Rabbit images for each operand should change to any number between 1 and 10
(inclusive). See Hint 3 and Hint 4.
Note: It is possible for the next number(s) to be the same as the current number(s).
h) Nothing should happen if the user clicks the ‘Check!’ button while at least one of the
text fields are empty, i.e. no errors should be thrown in this case.
Note: You can assume that only a numeric value will be entered into the text fields.
Hint 1: Use an array of JLabel components for the Rabbit images. The following constructor
may be helpful for the ‘plus sign’ icon.
public JLabel(Icon image)
A Rabbit image and ‘plus sign’ image are provided. You must use these images.
Hint 2: Consider using containers within other containers and using layouts intelligently.
Hint 3: Suggested approach for displaying images: look up the following method in the class
public void setIcon(Icon icon)
Hint 4: Suggested approaches for displaying a variable number of images: classes
java.util.Random OR java.lang.Math.
Note: All the necessary files should be placed in a directory called Task1.You can choose
whether to place the image files directly under Task1 or within a sub-directory. Whichever
approach you take, the images must be displayed on the GUI without having to move the
image files to different locations within your directory structure.
Also note that your application must run as expected from the command line on OpenJDK
Figure 3 GUI Resized
Task 2 [10 marks]
You may notice that entering a non-numeric value and clicking the ‘Check!’ button will cause
a run-time error on the console. Therefore, your second task is to improve the application
developed in Task 1 to ensure the user is only allowed to supply valid input values, i.e. a
number between 1 and 10 (inclusive). The application must still function as specified in Task
1 although you may remove the ‘Check!’ button if you wish.
Hint: Use another appropriate component in place of the text field.
Note: All the necessary files (including any reused ones from Task 1) should be placed in a
directory called Task2.
Documentation [10 marks]
You must include:
a. Generated Javadocs
b. Internal comments in your code.
c. User Manual. This should be no more than 2 pages and include how to run the program
(both how to start and how to use it).
Note: All documentation files should be placed in a directory called Documentation.
Extra Credit [5 marks]
Extra marks from this section can be used to top up your final grade for this project. Maximum
mark is still 50.
Further improve your application such that the maximum number of Rabbit images displayed
for each operand can be any number between 10 and MAX (inclusive), specified as a
command line argument. E.g. assuming your class is called SumItUpExtra, the command
Java SumItUpExtra 20
will launch a GUI similar to Figure 1 where the maximum number of Rabbit images displayed
per operand will be 20. Whenever a correct answer is entered, the number of Rabbit images
per operand will change to any number between 1 and 20 (inclusive). There should be no more
than 5 Rabbit images per row.
MAX must be calculated as follows.
If the last digit of your QM student number is 0-4, MAX = 20
If the last digit of your QM student number is 5-9, MAX = 25
If no command line argument is given OR a number outside the valid range is given, the
program must terminate printing out an appropriate error message to the console. You can
assume only a numeric value will be given as the argument.
Note: All the necessary files (including any reused ones from Task 1 and Task 2) should be
placed in a directory called ExtraCredit.
1. All three directories must be included in a zip file. The filename must be your QM
2. You should design your classes properly, following object oriented principles. E.g. do
NOT write everything in the main method, keep code repetition to a minimum (i.e. use
methods), do NOT use static methods unless there is a good reason. There will be
marks allocated for good design.
EBU4201 Introductory Java Programming 2022/23