Introduction

In this lab you will use the Java you have learned in lecture to write a small program.

Preparatory tasks

1.    Log in

2.    Start Eclipse

3.    Switch to the CVS Repository Exploring perspective

4.    Check out the SP2011-CSE115-Lab2 project from the Labs repository

5.    Switch to the DrJava perspective

Lab Tasks

A. Do the following in the DrJava interactions pane, declaring variables as needed.  Once you have finished, you must copy and paste the contents of the interactions pane into the DrJavaInteractions.txt file contained in the lab2 package of the src folder.  BE SURE TO COPY AND PASTE YOUR WORK BEFORE YOU CLOSE THE TERRARIUM WINDOW!

Create one example1.Terrarium object, put one example1.Caterpillar objects, two example1.Ant object and three example1.Butterfly objects inside it.  Make the caterpillars, both ants and one of the butterflies move by calling their respective "start()" methods.  Let the ants, butterfly and caterpillars move around for a few seconds, then call the "stop()" method on the ant, butterfly and caterpillar objects you started earlier, but only on those.

Once you have saved the contents of the interactions pane as described above, you should close the Terrarium window.  This will reset the interactions pane, erasing whatever is there (which is why you must save your work BEFORE closing the interactions pane).

B. Do the following by writing Java code in the EcoSystem.java file from the lab2 package using the Java editor.

First you will do the same thing you just did in the interactions pane: you will create some objects and call some methods on them.  Edit the constructor definition to do the following: create one example1.Terrarium object, put one example1.Caterpillar object, two example1.Ant objects and three example1.Butterfly objects inside it.  Make the caterpillars, both ants and one of the butterflies move by calling their respective "start()" methods.  Also call the "stop()" method on the ant, butterfly and caterpillar objects you started earlier, but only on those.

Make sure you save your changes.  In the Dr Java interactions pane, create an instance of lab2.EcoSystem.  What happens?  Can you explain?  Remove the calls to "stop()" from the code in your EcoSystem constructor.  Save your changes, and try things out in the interactions pane again.

Answer the following question (briefly) in the Explanation.txt file contained in the lab2 package of the src folder of the Lab 2 project.

What could you do to get the insects (catepillars, ants, etc.) to stop after a certain time when the program was running? You may not actually know how to write the code for this and that is fine. Explain "in English" the code you would like to write. (Note: There are actually many different answers and many different ways this could be achieved in programs, but you only need to discuss one way.)

Submitting your project to Web-CAT

In the DrJava perspective you should see the PackageExplorer view on the left of your screen.  Right-click on the project name "SP2011-CSE115-Lab2" and drag down to "Submit...".  Submit based on your official lab section.

If your submission was successfully sent to the Web-CAT server, you will see a window which says, "Your submission was successful."  Click "Finish" in this window.  If your submission was successfully received by the Web-CAT server you will see the following message displayed, "Your submission has been received by the Web-CAT Grader and is being processed."

Otherwise you will see a failure message.  This means your submission did NOT go through.  The most common problem is an incorrect password.  If this is the case, you must attempt your submission again.

Due Dates

Submission of Lab 2 is due the day before your recitation meets the week of February 14th. For your reference, consult the table below for due dates.

Grading Information

Coming soon.

Lab authored by Carl Alphonce, Adrienne Decker