1. From BlueJ to NetBeans
SWC 2.semester

2. Why change…? BlueJ is great for introduction to programming
Simple interface, few options
Graphical interface to classes and objects
Some tehnical details are hidden

3. Why change…? NetBeans is great for professional programming
Much more functionality
Better editor, debugger,…
Integration to database systems
A full-blown, stand-alone system
…but also more complex!

4. What is NetBeans? NetBeans is an open-source project
Originates from SUN Microsystems
Can - of course – be downloaded for free from the website
We use NetBeans SE (+ Java JDK)

5. What is NetBeans?

6. How do I… …create a new project? …add a new class?
…edit a class definition?
…write text to the screen?
…get input from the user?
…run a project?

7. Create a new project - BlueJ
Choose Project | New Project…

8. Create a new project - BlueJ
Enter project name, press ”Create”

9. Create a new project - NetBeans
Choose File |
New Project…

10. Create a new project - NetBeans
In Categories, choose ”Java”
In Projects, choose ”Java Application”

11. Create a new project - NetBeans
Enter project name and location

12. Create a new project - NetBeans

13. Create a new project - NetBeans
Why is there a ”Main.java” class…?
All Java programs must contain a method with this signature:
public static void main(String[] args)
This was hidden in BlueJ!
Think of Main as a ”System” class
When the program starts, the code in the main(…) method is executed

14. Add a new class- BlueJ
Press ”New Class…”
Enter class name

15. Add a new class- BlueJ

16. Add a new class- NetBeans
Highlight the bankaccount package!
Choose New | Java Class

17. Add a new class- NetBeans
Enter class name

18. Add a new class- NetBeans

19. Edit a class definition - BlueJ
Double-click on the class icon

20. Edit a class definition - BlueJ

21. Edit a class definition - NetBeans
Double-click on the class icon

22. Edit a class definition - NetBeans
Note the file panes in NetBeans

23. Edit a class definition - NetBeans
Why do red lines start to appear in the code, as soon as I start typing…?
The NetBeans editor continuously makes an analysis of the code, even before it is compiled
The editor highlights errors in the code by a waved red line, even before typing has been completed
Helpful…? Annoying…?

24. Edit a class definition - NetBeans
Yes, I know, but I am still typing!!

25. Edit a class definition - NetBeans
See hints by hovering mouse over (!)

26. Edit a class definition - NetBeans
Why do lists with method names pop up when I type…?
The NetBeans editor supports ”auto- completion”, i.e. it tries to predict what you will type next
Typically when calling a method with ”.”
Helpful, when you get used to it…

27. Edit a class definition - NetBeans
Available methods on the specific object/class
Documentation for each method

28. Writing text to the screen - BlueJ

29. Writing text to the screen - BlueJ

30. Writing text to the screen - NetBeans

31. Writing text to the screen - NetBeans
Need this code for actually executing the method

32. Writing text to the screen - NetBeans
Output written to the ”Output window”

33. Get input from the user - BlueJ

34. Get input from the user - BlueJ
Enter parameter value directly

35. Get input from the user - NetBeans
Not quite as simple to get input from a user in NetBeans
Two options
Use the Scanner class
Use a input dialog class
See chapter 3.6 in Big Java for details

36. Get input from the user - NetBeans
import java.util.Scanner; … Scanner in = new Scanner(System.in); String name = in.nextLine(); int balance = in.nextInt(); double area = in.nextDouble();

37. Get input from the user - NetBeans
import javax.swing.JOptionPane; … String value = JOptionPane.showInputDialog(”Limit”); int limit = Int.parseInt(value);

38. Running a project - BlueJ
We cannot as such ”run” a project in BlueJ – what should run..?
We usually create a ”system” class, that has a ”run”-like method
Create a System object
Right-click the object
Call the run method

39. Running a project - NetBeans
Choose Run | Run Main Project

40. Running a project - NetBeans
…or just click the green triangle (or press F6)

41. Running a project - NetBeans
Running a project always executes the main method in the Main class!
A project is automatically compiled when you save it
No reason to run a project in order to fix syntax errors

42. Other NetBeans features
A GUI Builder – build a GUI by drag-drop of controls. Code is auto-generated
A much more powerful debugger
More customisable
Easy integration to database systems
We will talk about additional features later on…