Your second assignment consists of four Java programs (fun fact: this picture is the offical Java mascot).

Getting Started

There is a starter project including all of these problems that you can access using the link below. Once you have the starter code set up, edit the program files so that the assignment actually does what it’s supposed to do (see the assignment handout), which will involve a cycle of coding, testing, and debugging until everything works. The final step is to submit your assignment.

You should write the code for your solution on your own. This assignment is not a pair assignment.

Note: You may only use concepts covered up through lecture on Tuesday, July 3, minus parameters, to solve these problems. In particular, you may not use Java concepts you may have learned previously such as parameters, instance variables, return, Strings, etc. As a general rule of thumb, any concepts mentioned in the readings up to but not including Chapter 5 are ok to use. If you have any questions about what is ok/not ok to use, please feel free to ask.

Assignment Files

To run the demo, download the file below and double-click to run. If you are unable to run it by double-clicking, right-click on the demo 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.


Q: I'm trying to print using colors, but I'm getting an error. Help!
A: You must add import java.awt.*; to the top of your program file; this specifies where Eclipse should look to learn about Colors.
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.