Assignment Files

To run the demo, download the JAR file below and double-click it to run. If you are unable to run it by double-clicking (e.g. due to an error message on Macs), instead right-click on the demo JAR file and click "Open".

Other Resources

Note: the "Debugging with Karel" handout still provides valuable debugging tips for Java programs! In particular, the debugger functions identically for Karel and Java programs.

F.A.Q.

Q: Why are my bricks the wrong size?

A: Are you using int sizes? Maybe you should use double for the highest precision. Also, are you sure your math is right? If there are 10 bricks per row, there are 9 gaps between them space at each side for centering. Also, are you sure you're using getWidth() and getHeight() to get the canvas size?

Q: Why can't I see the paddle?

A: Are you sure you're using the right values for the width/height of the overall game window? You should use getWidth() and getHeight() for this. Also try resizing the window larger to see if the paddle shows up.

Q: How many instance variables are ok to have? Can ___ be an instance variable?

A: We don't want to answer exactly what instance variables are okay or not okay. That is part of the assignment, for you to decide what is appropriate. You should follow the guidelines we have taught you for deciding that. If a value must be used through multiple methods over time and it can't be easily solved using a parameter or return, that is a good candidate for an instance variable. You should minimize the number of instance variables in your program and only use them if something truly needs to be an instance variable for the program to function.

Q: I'm having trouble getting Eclipse to work! Help!

A: Please make sure you followed the instructions in our Eclipse Guide above. If you are still having trouble, please come to Colin or Annie's office hours, or stop by the LaIR.

Q: Eclipse is giving me a strange message about a file being "out of sync" with the file system. It says I can press F5 to refresh the file. What does this mean?

A: This happens if you edit/change your file outside of Eclipse. Just press F5 and Eclipse will show you the newest version of the file.

Q: I didn't like the program name, such as Snowman, so I renamed it to my own name such as DaveIsGreat. That is okay, right?

A: No. For grading purposes, we need you to leave the program names the way we named them.

Q: How do I turn in the assignment? How do I know if my submission was successful?

A: Please see the Eclipse Guide link above for more information about submitting.

Q: Why doesn't my Java program say "[completed]" in the top status bar when it is done?

A: This is often because your program contains an infinite loop. Make sure all of your loops are terminating properly when your program is finished! Also see the debugging handout above for how to use the Eclipse debugger to track down and squash bugs.

Q: Will my solution get full credit? Is it written in the style you want? Will I get marked off for this code?

A: In general we cannot answer these kinds of questions. We call this "pre-grading." The section leader/TA/instructor can't look over your entire program for mistakes or tell you exactly what things you will get marked off for; we don't have the resources to provide such a service, and even if we did, we want you to learn how to gain these intuitions on your own. We'll grade you on the guidelines in the homework document and style guide, and we can help you with specific issues and questions about your code, but we cannot pre-evaluate your entire program for you or give you advance warning about every possible mistake or violation.