Java Reference
In-Depth Information
You'll begin by test-driving the app, using it to calculate 15% and 10% tips. Then
we'll overview the technologies you'll use to create the app. You'll build the app's GUI
using the NetBeans and JavaFX SceneBuilder. Finally, we'll present the complete Java
code for the app and do a detailed code walkthrough.
25.5.1 Test-Driving the Tip Calculator App
Opening and Running the App
Open the NetBeans IDE, then perform the following steps to open the Tip Calculator app's
project and run it:
1. Opening the Tip Calculator app's project. Select File > Open Project… or click the
Open Project… ( ) button on the toolbar to display the Open Project dialog.
Navigate to this chapter's examples folder, select TipCalculator and click the
Open Project button. A TipCalculator node now appears in the Projects window.
2. Running the Tip Calculator app. Right click the TipCalculator project in the
Projects window, then click the Run Project (
) button on the toolbar.
Entering a Bill Total
Using your keyboard, enter 34.56 , then press the Calculate Button . The Tip and Total
TextField s show the tip amount and the total bill for a 15% tip (Fig. 25.9(b)).
Selecting a Custom Tip Percentage
Use the Slider to specify a custom tip percentage. Drag the Slider 's thumb until the per-
centage reads 20% (Fig. 25.9(c)), then press the Calculate Button to display the updated
tip and total. As you drag the thumb, the tip percentage in the Label to the Slider 's left
updates continuously. By default, the Slider allows you to select values from 0.0 to 100.0,
but in this app we'll restrict the Slider to selecting whole numbers from 0 to 30.
25.5.2 Technologies Overview
This section introduces the technologies you'll use to build the Tip Calculator app.
Class Application
The main class in a JavaFX app is a subclass of Application (package javafx.applica-
tion.Application ). The app's main method calls class Application 's static launch
method to begin executing a JavaFX app. This method, in turn, causes the JavaFX runtime
to create an object of the Application subclass and call its start method, which creates
the GUI, attaches it to a Scene and places it on the Stage that method start receives as
an argument.
Arranging JavaFX Components with a GridPane
Recall that layout containers arrange JavaFX components in a Scene . A GridPane (package
javafx.scene.layout ) arranges JavaFX components into columns and rows in a rectangu-
lar grid.
This app uses a GridPane (Fig. 25.10) to arrange views into two columns and five
rows. Each cell in a GridPane can be empty or can hold one or more JavaFX components,
including layout containers that arrange other controls. Each component in a GridPane
can span multiple columns or rows, though we did not use that capability in this GUI.
 
 
 
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