Exception Handling

Introduction to JavaFX
9-11-2013
Summary of Exception Handling
Graphical User Interfaces (GUIs)
Introduction to JavaFX

HW#2 posted; due 9/23/2013
Reading Assignment:
Java Tutorial on GUIs: Creating a JavaFX GUI




First consider a classic D6
0.0
1.0
1 2 3 4 5 6
1 5 2 3 4 6
3
5
loadedSide
loadFactor
0
100 50
Item 40: Use checked exceptions for
recoverable conditions and run-time
exceptions for programming errors

Item 42: Favor the use of standard
exceptions


Exception handling is not supposed to
replace a simple test.
try {
s.pop();
} catch(EmptyStackException es) {}

if (!s.empty()) s.pop(); // is much better

terrible design
too much overhead!
Item 39: Use exceptions only for
exceptional conditions

A well-designed API must not force its client
to use exceptions for ordinary control flow.
Do not micromanage exceptions.
try { s1 } catch(Exception e) {};
try { s2 } catch(Exception e) {};
etc.


Item 43: Throw exceptions appropriate to
the abstraction.
catch-all
try { s1; s2; } catch(
Do not squelch exceptions.
Image loadImage(String s) {
try {
// lots of stuff
} catch(Exception e) {} // so there!
}

Item 47: Dont ignore exceptions.
JavaFX is a set of graphics and media
packages that enables developers to design,
create, test, debug, and deploy rich client
applications that operate consistently
across diverse platforms.
visual effects, animations, sound
mobile phones, consumer, television, desktop
scene-graph-based programming model
The JavaFX SDK is included in JDK 7

Overview of JavaFX
The Java Tutorial on GUIs: Creating Java
Graphical User Interfaces:
Creating a JavaFX GUI
JavaFX Demos and Samples
scroll to bottom, then download the zip file
Javadoc for JavaFX
Eclipse & Netbeans have good tutorials on using
JavaFX

1. Get set up

2. Create the Framework

3. Define the UI

4. Lay out the UI controls

5. Deploy
The first step in getting started with JavaFX
is to download and install the Java SE 7 JDK,
which includes the JavaFX runtime libraries
and utilities. See the JDK 7 and JRE 7
Installation Guide for instructions.
JavaFX Scene Builder provides a simple way
to build the UI for your application and
connect it to the application logic. To install
this tool, see Installing JavaFX Scene Builder.

Each JavaFX application has a similar
framework. The main class for the
application extends the Application class.
The start() method sets up and shows the
stage, which contains the UI for the
application. See Hello World, JavaFX
Style for information on setting up a
NetBeans project and creating a simple
application.

The stage for the application interface
contains one or more scenes, which in turn
contain the controls, shapes, and images
that make up your user interface. See Using
JavaFX UI Controls for information on
defining controls such as buttons, labels,
and text fields for your UI.
The JavaFX Scene Builder's Library panel
provides the same UI controls that are
available in the SDK. See Library Panel for
more information.

After you decide what controls you want in
your UI, use one of the built-in layout panes
to manage the size and position of the
controls. See Using Built-in Layout
Panes for information on setting up your UI
controls to create the screens for your UI.
An easier way to lay out your UI is available
with the Library panel in JavaFX Scene
Builder. You can also manage layouts in
JavaFX Scene Builder using the Inspector
panel. See Inspector Panel for information.

JavaFX applications run on a desktop, in a
browser, and by using Web Start. When your
application is ready, create the files that
your users will run. See Getting Started in
Deploying JavaFX Applications for
information on packaging and deploying
your application.

1. Set up for NetBeans (Eclipse is similar)








Download NetBeans IDE bundled with JavaEE
and install


Software or Resource Version Required
NetBeans IDE 7.3
Java Development Kit
(JDK)
7 update 10 or more
recent
JavaFX SDK
(cobundled with JDK)
2.2.4 or more recent
2. Create a JavaFX project in NetBeans
File | New | Project & select JavaFX, next
Give the project a name, and select finish

Demonstrated in class










package hellojavafxworld;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

/** The main() method is ignored in correctly
deployed JavaFX application. main() serves only as
fallback in case the application can not be launched
through deployment artifacts, e.g., in IDEs with
limited FX support. NetBeans ignores main().
@param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
}

public class HelloJavaFXWorld extends Application {
@Override
public void start(Stage primaryStage) {
Button btn = new Button(); // create a button
btn.setText("Say 'Hello World'");
btn.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
System.out.println("Hello World!");
}
});
// continued on next slide


// continue HelloJavaFXWorld class

StackPane root = new StackPane();
root.getChildren().add(btn); // add the button

Scene scene = new Scene(root, 300, 250);

primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}


Setup JavaFX for either NetBeans or Eclipse
(your choice)

If using NetBeans, view the video
Building your first JavaFX application (this
uses NetBeans 7.1, but is still very useful)

Customize the default application in some
way