BlueJ is an IDE that provides an editor, compiler and debugger for developing and deploying Java applications. It is also a user friendly tool which makes object-oriented programming even easier.

Start BlueJ

Double click on the icon and the BlueJ window will appear.

Exit BlueJ

1. Select Project -> Quit from the menu OR
2. Click X

Projects in BlueJ

Create a Project (using menu)

Project -> New

Provide a name for project on the prompt

Open an existing project

Project -> Open

Select project by browsing to right location of project

Adding Classes

Provide a name for class on prompt

1. Click New Class on left side OR
2. Edit -> Add Class from File

Editing Classes

Once the class is created you can:

1. Double click on the class icon OR
2. Right click and choose Open Editor

It gives you a nice constructor for reference. You can delete or make changes accordingly. Cool thing about this editor is that it enables syntax highlighting. When you compile, the project gets automatically saved, otherwise choose Class -> Save and close.

Saving a project

Removable device

Save As on CD-RW, flash drive etc...

On Blackboard

Assignments -> Labs -> ViewAssignment

You can upload the project and save. Do not submit until you are ready to submit, only save.

On the machine

Bad Idea.

Email

Email it to yourself.

Compiling a project

Uncompiled project has stripes on it. If project doesn’t compile then it means there is a syntax error in the class. Good thing about BlueJ is that it highlights the line which has error and tries to tell what is missing, expected or wrong.

Running a project

BlueJ Object Bench

Right click on class and choose new ClassName(). This creates a red object on lower left of window. It also allows to provide a name for instance.

You can manipulate the data by right clicking and choosing a method. A method requiring arguments will prompt for input in another window.

Main Method

Right click on class icon and choose main method. The program will run and print out the output on a console window.

Applets, AWT, Swing

GUI