The simulation at the top of this topic was created 17 years ago with JDK1.0.2
You might need to change some of the code for latest JDK.
However, you can compile it with JDK1.0.2 without error message.
JDK102.zip is added as attached file. You can download it and use it to compile the above code.
There is another [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=365.0]Ejs version of traffic control simulation[/url]
You can view how it was created and add new condition if you install EJS.
You can find ejs download link with google search:EJ? download.