M/F 2:30-3:20   
in G01 Gates Hall

CS 1130: Transition to OO Programming

Spring 2016

Java Expressions

There is a PDF version of these instructions, if you would prefer to have that instead.

This lab serves two purposes. First, it is designed to get you started with DrJava immediately. Second, gives you hands on experience with Java expressions, which we talked about on the first day of class. With that said, you are not expected to be be writing any programs for this lab; for the most part you will just be using DrJava as a glorified calculator.

Getting Started with DrJava

To open DrJava in a ACCEL-lab computer, find the following folder:

Start ⇒ All programs ⇒ Class Files ⇒ DrJava

Inside the DrJava folder will be a .jar file; double click on this file to start DrJava.

If your primary computer is a laptop, bring it to the lab as it is an excellent opportunity to get started with DrJava on your machine. Follow the instructions on the DrJava page. Feel free to ask a consultant for help if you run into problems; that is why they are there.

Lab Instructions

Below is a list of expressions. For each expression, we would like you to first compute the expression in your head, without DrJava. You should write down what you think the value is in the second column of the table. If you have no idea, you should write "?". Once you have done that, you should then use DrJava to compute the same expression. Simply cut and past the expression from this webpage into the Interactions pane, and hit the ENTER key to have the expression evaluated. You should write the result in the third column.

If the two values are different, you should try to figure out why DrJava gave the answer that it did. Come up with a reasonable explanation and put it in the final column. You are not really being graded on these labs (see Turning In the Lab), so you should just make your best guess at what is happening; your answer will help the instructor and consultants understand how to better aid you.

As part of this lab, you may find it convenient to enlarge the Interactions pane. To do this, put the mouse on the horizontal bar running across the entire window, hold down the mouse button, and drag the bar upwards. Also, you can use the up-arrow key to obtain a previous expression; then you can edit the expression and hit the return key to have the modified expression evaluated.

As this is the first lab, it is a little shorter than some of the future labs. With that said, do not waste time! If you don't understand something, ask your lab instructor or a consultant immediately. It is very important that you understand how each expression is evaluated, so if an answer doesn't make sense, ask someone. The lab instructors and consultants are in the lab to help. They will look over your shoulder from time to time and give you advice.