problem executing dos commands in program

hey all,
i am workin on a program for school and runnin into a snag. we are supposed to make a program that simulates traffic conditions in a town and determine whether adding a dedicated left turn arrow eases conjestion ornot. i would like to go a step further and create a little print out of these "cars" in my queues. the problem i forsee is that java has no cls. i have researched online and found an ingenious solution that just uses dos commands. well i am having trouble getting them to execute correctly. here i hope is a screenshot of my problem:
Attachment 2046
sorry about all the message boxes. i forgot to take them out. but as you can see the error isin the runtime command. if you can see any error i have or know of an alternate way to force java to cls i would appreciate any help.

if the pic did not post ill type in the code when i get a chance
thanks for any help.

If you want fancy output, I'd use a GUI such as is available with the Swing library.