CMPSCI 377: Operating Systems
Lab 1: Java Refresher

Due: Feb. 21, 2003 23:30

Purpose of Assignment

This assignment is intended to bring you up to speed on the subset of Java you will need for this course (if you do not have it yet). Anyone who cannot finish this assignment on time does not have the necessary programming skills to complete this course successfully, and should drop the course. Since the assignment is not really related to operating systems, it will only count for 8% of your lab grade.


Programing for this lab may be done using the Computer Science Ed Lab workstations. The java compiler is envoked with the javac command, and the java virtual machine is started with the java command.

Every student in CMPSCI377 has an edlab account; the default username for the account is the first letter of your first name followed by your last name; if your name is Allen Roberts, for example, your username would be aroberts. The default password is your student ID number. If you have trouble accessing your account, please ask the monitor or someone in the CSCF office (in the CS Dept building). If you are logging in remotely, you should use elnux{0-34}.

Where to do your work

For this lab, place your final submission in the following directory:


If your files are not located in the right place at the time of submission, then your assignment will not be accepted. You may check this by using the checkhw lab1 shell command (just as you have done for lab 0).

The Problem

For lab 2, we will be solving a problem involving multiple, coordinated robots (with which we will study threads and synchronization). In short, there will be some set of robots of various colors (red, green, and blue), and some set of goals (red, green, blue, and black). The robots and goals will "live" on a discrete grid of a specific size (think graph paper). Some grid squares will be occupied by obstacles. In lab 2, the task will be for the individual robots to move around on the grid and "eat" goals without running into each other or any obstacles.

We will prepare for lab 2 here by performing two of the initial steps. First, we will parse a file that contains information about where the robots, goals, and obstacles are located. This file name will be specified as the first command-line parameter. Second, we will display a map of this world within a window.

Here is one example of a map file.


The semantics of this file are:

Your program must parse this file and place the information into an appropriately-designed data structure. Your program should detect and trap any errors that might exist in the file and display an appropriate error message. Possible errors include:

The output is a map of the grid that shows the obstacles, robots, and goals. Here is an example that corresponds to the map file above:

Here, goals are shown as triangles and robots are shown as "Pac-Men". In your implementation, these may be drawn in any way you like.

What to Hand In

Everyone must hand in their own work for this lab (in later labs, you will be able to work in pairs).

Place in your Hand-In directory the following:

We will test your program with a variety of maps, including:

Your program should produce an appropriate map for the first three files and appropriate error messages for the last five files.


This lab is worth 8% of your lab grade. This grade will depend on:

Some Hints

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Andrew H. Fagg