From BlueJ to NetBeans SWC 2.semester

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 project Originates from SUN Microsystems www.netbeans.org Can - of course – be downloaded for free from the website We use NetBeans 6.9.1 SE (+ Java JDK)

What is NetBeans?

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 - BlueJ Choose Project | New Project…

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

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

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

Create a new project - NetBeans Enter project name and location

Create a new project - NetBeans

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

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

Add a new class- BlueJ

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

Add a new class- NetBeans Enter class name

Add a new class- NetBeans

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

Edit a class definition - BlueJ

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

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

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…?

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

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

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…

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

Writing text to the screen - BlueJ

Writing text to the screen - BlueJ

Writing text to the screen - NetBeans

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

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

Get input from the user - BlueJ

Get input from the user - BlueJ Enter parameter value directly

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

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();

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

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

Running a project - NetBeans Choose Run | Run Main Project

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

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

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…