Using BlueJ 

BlueJ is a Java progamming editor, with lots of other features. That means it is an IDE (Integrated Devlopment Environment) - a lot more than just an editor.  BlueJ was created by some University lecturers for their students.  It is especially designed to make OOP (Object-Oriented Programming) easier and more understandable.

If you need a copy of BlueJ, or you want more information, visit their web-site:  http://www.bluej.org
 

Installation

BlueJ should run just by copying it onto your hard-disk - installation is not required.  However, you may need to run SelectVM one time so BlueJ finds the Java compiler.  After that, start by running the BlueJ.exe file.
 

Projects

In BlueJ, you must create a new project before you can edit or run a Java class.  When you name your project, BlueJ will automatically create a directory (folder) for saving the Java classes in that project.  BlueJ does a very good job of automatically saving files, so you never really need to press the Save button (if you are the nervous type, go ahead and press save).  The next time you start BlueJ, it will remember the name of the project you had open before - as long as you are the only person using the computer.  If not, you can make your own copy of BlueJ and it will always load your project automatically.
 

Classes

Your project can have as many classes as you want.  Each class is displayed in a little box.  BlueJ draws arrows to show how classes are connected - when one class uses another.

Click the [New Class] button to add a new class to your project.  Type a [Name] for the class (without .java) and click on the type of class you want.  For FIS students, you'oll probably start with easyApp classes.  Whichever type you choose, BlueJ will use a template to write some of the commands for you - the public class header,  public static void main..., maybe some sample methods, etc.  The easyApp template includes a sample Button, TextField, Menu, and the actions method.

If your class extends EasyApp, you will need to add EasyApp to your project.  To do this, open the [Edit] menu and select [Add Class from File], find a copy of EasyApp and open it.  Then it should appear in the Project window.
 

Editor

After creating a class, double-click on the box to open the editor.  Type your Java commands and then click [Compile] when you are ready.  If you have a synatx error, the editor will highlight the line with the error and print an error message at the bottom of the window.

You will notice there is no run button here.  You can leave the editor open when you return to the project window to run the program, or close it if you prefer
 

Running a "Program"

In BlueJ, everything is Object-Oriented.  So you don't really "run a program".  Instead, you instantiate an object from a class.  You don't actually need a main method - although you can do it that way if you wish.  To start the "program", right-click on the "main class" (the one that should start) and choose either new Talker() (the class) or void main.  Either way, you will see another box - just click [Ok] to start.
 

Stopping

If you made a new Talker(), you'll see a red box at the bottom of the project window.  This is a control box that can inspect the object or remove the red box.  You still need to click the [x] on the window.  If you started by running main, then you stop the program the normal way - there is no inspector box.
 

Inspector

The inspector shows all the methods in your object.  It will also execute any method you choose.  It will ask you to type in values for all of the parameters required by the method.  This is an excellent tool for testing parts of your object.  You'll learn more about this later.