Creating and Running programs in BlueJ

This page has lots of pictures and will take a long time to load if you are using a slow modem connection.

You need to have downloaded and installed BlueJ before completing the following steps.

Download the java files you need from the class web site. You don't have to put them in the BlueJ folder, just remember where you download them to on your computer.
Start BlueJ by either clicking on the icon you created when you downloaded and installed BlueJ or by navigating to the BlueJ directory and double clicking on the bluej.bat icon.

When BlueJ is up and running go to the Project Menu and select New
This opens a new window.

From this window type in the name of the new project in the text field File name. The name of the project does not have to be the same as the name of the java file you will later add to the project. It can be anything you want.
After giving the new project and name and clicking Create you see the new project.

There aren't any classes or code associated with the project yet. The icon that looks like a piece of paper is just a simple text file that acts as the projects readme file. You can double click on it to add comments about the project as a whole or write notes to yourself on things that need to be done. You probably won't use it much at first.
Now you need to add the code or java file(s) to the project. To add the existing file to the project click on the Edit menu and then select Add Class from File...
A new window pops up that allows you to select the file you want to add. Only files that end in .java are shown.

I have had trouble with the Up One Level icon. Sometime it has worked, but sometime I have had to use the upside down triangle next to the bluej folder to get the drop down list to show up and then navigate to where the file is I want to add. Navigate to where the file is you want to add. Click on it to add it to the project.
Now the new file / class has been added to the file. It shows up with diagonal lines because it has not been compiled yet.
To edit a program / class double click on that program / class and it pops up in a text editing window.
You can type in the window to change the program. You save the program by clicking on the Class menu and selecting Save. You can attempt to compile the program by clicking the Compile button. Any errors will show up in the text area at the bottom of the edit window. If an error occurs the line the error is on is highlighted in gray. After compiling the program and getting it to work close the editing window w and go back to the project window. The program / class icon no longer has diagonal lines across it.
To run the program right click on the icon that has the main method in it. This brings up a menu that allows you to carry out various actions. (You could also compile classes here.) Select the menu option void main(args). This causes the main method of the class to be executed.
Another menu pops up that asks what parameters or information you want to pass to the method, in this case main. In this class we won't normally pass any information to method main so just click OK.
This causes the program to run.
If you want to clear out the terminal window before running the next program then be sure to click on the Options menu and pick Clear.
Later, when you write your own classes you will create new classes in BlueJ by clicking on the Edit menu in the project window and selecting New Class... This causes a new class to be brought up. The new class has lots of example code that should be deleted.
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