From BlueJ to NetBeans
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Transcript of From BlueJ to NetBeans
Why change…?BlueJ is great for introduction to
programming◦Simple interface, few options◦Graphical interface to classes and
objects◦Some tehnical details are hidden
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!
What is NetBeans?NetBeans is an open-source
projectOriginates from SUN
Microsystemswww.netbeans.orgCan - of course – be downloaded
for free from the websiteWe use NetBeans 6.9.1 SE (+
Java JDK)
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?
Create a new project - NetBeansWhy 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”
classWhen the program starts, the
code in the main(…) method is executed
Edit a class definition - NetBeansWhy 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…?
Edit a class definition - NetBeansWhy 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…
Edit a class definition - NetBeans
Available methods on the specific object/class
Documentation for each method
Get input from the user - NetBeansNot quite as simple to get input
from a user in NetBeansTwo options
◦Use the Scanner class◦Use a input dialog class
See chapter 3.6 in Big Java for details
Get input from the user - NetBeansimport java.util.Scanner;…Scanner in = new Scanner(System.in);…String name = in.nextLine();…int balance = in.nextInt();…double area = in.nextDouble();
Get input from the user - NetBeansimport javax.swing.JOptionPane;…String value = JOptionPane.showInputDialog(”Limit”);
…int limit = Int.parseInt(value);
Running a project - BlueJWe 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
Running a project - NetBeansRunning 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