Assignment 1

Assignment #1

Due: Sat, Jan 27

Objective

To practice with Java syntax, both in writing classes and in writing executable programs. Also to practice with Java compilation and execution of programs.

Task:

I have provided an example of two C++ classes, and your task will be to translate these into two Java classes (with some slight differences specified below), and also to write a small test program that uses these classes.

Details:

The following files contain two classes, called Display and Timer.

timer.h - declarations of both classes
timer.cpp - definitions of class members, for both classes

This example uses composition and creates Timer as a new type that represents a digital timer, which looks like a clock displayed in 24-hour time (like military time).

You are to translate these two classes into Java classes Display and Timer. Functionality, permissions (public/private), method names, and other class details should match those of the given c++ classes except where noted in these guidelines:

Write the Display class in the file Display.java, and write the Timer class in the file Timer.java
In the C++ code, both classes have a show() member function. To make this more versatile, convert these in your Java classes into toString functions instead. This means you will return a string representation of the object from inside the class, rather than print to the console.
In the C++ code, there is an overload of operator+ for the Timer class. Since Java does not allow operator overloading, translate this to a Timer class method called add(). The add function should have the same functionality as the operator+ function in the C++ code.

You are also to write a sample test program, described below.

Test Program

I have provided one small file with some hard coded calls, in the file Sample.java. This illustrates the syntax of expected calls to public methods of class Timer.

You are to write your own test program, in a class called TimerTest (filename TimerTest.java). It should do the following:

Create two objects of type Timer
Prompt and ask the user to enter (from the keyboard) values for hours and minutes for the first timer. Attempt to set this as the clock time on the first timer. Whenever the attempt fails, make the user re-enter the data
Repeat this user-entry process for the second timer
Print out the values on both timers
Add the two timers together, and print the result
Increment each timer 20 minutes, printing out the results as you go

A sample of the expected execution of this test program appears below.

Sample run of TimerTest.java

(keyboard input is underlined, for clarity)

Enter hours for first timer: 34
Enter minutes for first timer: 45
Invalid timer values. Try again.
Enter hours for first timer: 12
Enter minutes for first timer: 54

Enter hours for second timer: 9
Enter minutes for second timer: 70
Invalid timer values. Try again.
Enter hours for second timer: 9
Enter minutes for second timer: 48

t1 = 12:54
t2 = 09:48

t1 added to t2 is: 22:42

Incrementing t1 by 20 minutes
12:55
12:56
12:57
12:58
12:59
13:00
13:01
13:02
13:03
13:04
13:05
13:06
13:07
13:08
13:09
13:10
13:11
13:12
13:13
13:14

Incrementing t2 by 20 minutes
09:49
09:50
09:51
09:52
09:53
09:54
09:55
09:56
09:57
09:58
09:59
10:00
10:01
10:02
10:03
10:04
10:05
10:06
10:07
10:08

Testing and Submitting

You can test your code on either program.cs.fsu.edu or linprog.cs.fsu.edu. The Java2 SDK 1.5.0 is installed on both of those machines (this is the Java Standard Development Kit). Remember that we've discussed how to compile java code files with the javac command, and how to run a main program with the java command. Example:

  javac Fraction.java		// this would compile the Fraction class
  javac Qwerty.java		// this would compile the Qwerty class

  java Qwerty			// this would run the main program in the
				//   Qwerty class

You will submit these files:

  Display.java
  Timer.java
  TimerTest.java

To prepare your submission, we will use one more Java tool -- the jar (java archive) utility. This is similar to the tar (tape archive) utility common in unix systems. Pack up your files into a jar archive file with this command:

  jar cvf hw1.jar Display.java Timer.java TimerTest.java

E-mail this jar file (hw1.jar) to me (myers@cs.fsu.edu) by the due date. Your e-mail subject should be HW1-SUBMIT. Include your name and section in the e-mail body. Please only submit ONCE, unless you make a mistake and need to correct it (before the due date) -- and minimize this. Only the last submission will be graded.

Your submission e-mail needs to come either from your CS account (preferred) or your garnet/mailer account.

Suggestion

The easiest way to mail a file from your CS account is to send the e-mail directly from your CS address. I'd suggest using the "pine" e-mailer from there. HOWEVER, it is better to do this when logged on to shell.cs.fsu.edu (not program or linprog). If you need help with doing this, see me.