Designing Graphical Interfaces - Beginning Java Programming: The Object-Oriented Approach - page 546

@Override
public void actionPerformed(ActionEvent arg0) {
double mass;
double height;
try {
mass = Double.parseDouble(txtMass.getText());
height = Double.parseDouble(txtHeight.getText());
} catch (NumberFormatException e) {
JOptionPane.showMessageDialog(self,
"Please enter a valid number for mass and height.",
"Input error",
JOptionPane.ERROR_MESSAGE);
return;
}
double result = calculateBMI(mass, height);
JOptionPane.showMessageDialog(self,
"Your BMI is: " + (Math.round(result*100.0)/100.0),
"Your BMI result",
JOptionPane.PLAIN_MESSAGE);
}
});
*/
}
protected double calculateBMI(double mass, double height) {
return mass / Math.pow(height/100.0, 2.0);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() { new BMICalculatorFX(); }
});
}
}
The first thing to do is to figure out a way to show a simple window using JavaFX. In JavaFX, the
main actor is called an application , and it can manage and show various stages . For this simple
JavaFX application, this leads to the following:
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class BMICalculatorFX extends Application {
//private final JTextField txtMass = makePrettyTextField();
//private final JTextField txtHeight = makePrettyTextField();
//private final JButton btnCalc = makePrettyButton("Calculate BMI");
public BMICalculatorFX() {
/*
btnCalc.addActionListener(new ActionListener() {
@Override