lanching same JavaFx window after closing it - javafx

Question

I am open A JavaFX application using a Jframe.And after using JavaFx application window i close the window .And want to again open this same Javafx window but an error occur-
java.lang.IllegalStateException: Application launch must not be called more than once

Answer 1

As stated in the documentation, calling Application.launch(...) more than once will result in an exception:
public static void launch(String... args)
Launch a standalone application. This method is typically called from
the main method(). It must not be called more than once or an
exception will be thrown.
If you need to mix Swing and JavaFX, you should embed the JavaFX pieces in a JFXPanel and place it in a JFrame. You can then show and hide the JFrame as often as you need, using setVisible(...). An application working this way will not have an Application subclass at all.
Mixing Swing and JavaFX is tricky, and not recommended for beginners. The problem is that each toolkit has its own UI thread, and all access of the UI must be executed on the correct UI thread (i.e. the AWT event dispatch thread for Swing/AWT components, and the JavaFX Application Thread for JavaFX components). Data that is shared between both must provide proper synchronization to ensure that it is safely accessible from multiple threads.
Here is a very simple example. Clicking the button will show the window with FX content. If you close that window, and then click the button again, it will be shown again.
import java.awt.BorderLayout;
import java.util.Random;
import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Scene;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart.Data;
import javafx.scene.chart.XYChart.Series;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class SwingFXExample {
private JFrame mainFrame ;
private JFrame fxFrame ;
private JFXPanel fxPanel ;
public SwingFXExample() {
// must be on Swing thread...
if (! SwingUtilities.isEventDispatchThread()) {
throw new IllegalStateException("Not on Event Dispatch Thread");
}
mainFrame = new JFrame();
JButton showFX = new JButton("Show FX Window");
JPanel content = new JPanel();
content.add(showFX);
mainFrame.add(content, BorderLayout.CENTER);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fxFrame = new JFrame();
fxPanel = new JFXPanel();
fxFrame.add(fxPanel);
fxFrame.setSize(640, 640);
fxFrame.setLocationRelativeTo(null);
Platform.runLater(() -> initFX());
showFX.addActionListener(event -> fxFrame.setVisible(true));
}
private void initFX() {
// must be on FX Application Thread...
if (! Platform.isFxApplicationThread()) {
throw new IllegalStateException("Not on FX Application Thread");
}
LineChart<Number, Number> chart = new LineChart<>(new NumberAxis(), new NumberAxis());
Series<Number, Number> series = new Series<>();
series.setName("Random data");
Random rng = new Random();
for (int i = 0; i <= 10; i++) {
series.getData().add( new Data<>(i, 100*rng.nextDouble()) );
}
chart.getData().add(series);
chart.setOnMouseClicked(evt -> {
if (evt.getClickCount() == 2) {
System.out.println("Double click!");
}
});
fxPanel.setScene(new Scene(chart, 400, 400));
}
public void showMainWindow() {
mainFrame.setSize(350, 120);
mainFrame.setLocationRelativeTo(null);
mainFrame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
SwingFXExample app = new SwingFXExample();
app.showMainWindow();
});
}
}