Exercise 04: Rock Around the Clock - Part 1
Katarina Elevator in Stockholm, Foto by Arjan Richter
This week’s lab work is intended to get you to implement parts of a class that is given for you. You are also to begin to see the idea of modularization, that is, splitting up code into classes.
Pre-lab
P0. Which of the following expressions returns true? After writing your answers on paper, open the CodePad in BlueJ and try it out.
| Expression | Your Answer | Actual Value |
|---|---|---|
| ! (4 < 5) | ||
| ! false | ||
| (2>2) | ||
| (4==4) && (1<0) | ||
| (34 != 33) && !false | ||
| (43 < 42) && (rabbitCount > dogCount) | ||
| test = (3 < 4) |
P1. Write an expression using boolean variables a and b that evaluates to true when either a and b are both true or both false.
P2. Write an expression using boolean variables a and b that evaluates to true when only one of a and b is true, and which is false if a and b are both true or both false. This is called the exclusive-or.
P3. Consider the expression (a && b). Write an equivalent expression (one that evaluates to true at exactly the same values for a and b) without using the && operator.
P4. Americans are kind of strange about numbers and units. They write the days backwards, they use pounds and inches instead of kilograms and centimeters, and they have this bizarre 12-hour clock they use with “am” and “pm”.
- What time is “12:00 am” on the German (24-hour) clock?
- What time is “12:00 pm”?
- What time is “03:00 am”?
- What time is “05:30 pm”?
What To Hand In
You need to upload 2 Files to Moodle:
- Your Lab Report as PDF with the extension .pdf (max. 5 pages)
- The source code folder containing all BlueJ projects compressed with ZIP and the extension .zip
Assignment
Source Code for this exercise: https://github.com/htw-imi-info1/exercise04
Clock time
Adapt the clock-display to display the time American-style (i.e. 12-hour clock and am / pm). You will have to include the am/pm in the time! Make sure your displayString has exactly this format: 06:15 am
Also, if you want to introduce a new parameter to the setTime method, make sure that the old setTime method is still working using 24h-Format. Same goes for the constructor - add a third constructor if you want an alternative parameter list.
There are at least two ways to implement the clock display - one keeps the time internally as a 24-hour clock and adapts the output, the other keeps the time internally as it is displayed. Chose one way for now. You will need to implement the display the other way next week.