From BlueJ to NetBeans

nutmegactSoftware and s/w Development

Nov 11, 2012 (4 years and 8 months ago)

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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…