From BlueJ to NetBeans

From BlueJ to NetBeansSWC 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

projectOriginates from SUN

Microsystemswww.netbeans.orgCan - of course – be downloaded

for free from the websiteWe 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 - 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

Add a new class- BlueJPress ”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 - 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 - NetBeans

Yes, I know, but I am still typing!!

Edit a class definition - NetBeans

See hints by hovering mouse over (!)

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

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 - 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 - NetBeans

Choose Run | Run Main Project

Running a project - NetBeans

…or just click the green triangle (or press F6)

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

Other NetBeans featuresA GUI Builder – build a GUI by

drag-drop of controls. Code is auto-generated

A much more powerful debuggerMore customisableEasy integration to database

systemsWe will talk about additional

features later on…