How to Access JavaFX Virtual Keyboard (FXVK) Using Open JDK 15 or beyond? - javafx

Question

I use the javafx virtual keyboard with open jdk 8. At times I have to access the virtual keyboard to prevent it from displaying when certain text fields get focus. An example of this is a screen where an operator has to scan in multiple barcodes. This virtual keyboard gets in the way. With open jdk 8 we were able to disable the virtual keyboard like this:
FXVK.detach(); //after importing "com.sun.javafx.scene.control.skin.FXVK"
We are now upgrading to open jdk 15 and building our UI with gradle. "com.sun.javafx.scene.control.skin.FXVK" is no longer accessible with a modular project with gradle. I don't believe using a different virtual keyboard is an option so can anyone explain how to access this FXVK class after java 8?
Is there a way to use --add-exports or --patch-module with a JAR to patch JavaFX to gain access to the internal class?
Below is the code for a sample project that shows this problem.
This is the JavaFX Application class that simply displays a text field and shows the code I could use with java 8 to not show the virtual keyboard.
package com.test.sampleapp.application;
////not accessible in java 15
//import com.sun.javafx.scene.control.skin.FXVK;
import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class Main extends Application{
public static void main(String[] args)
{
launch(args);
}
#Override
public void start(Stage primaryStage) throws Exception
{
Label label = new Label("Text field below");
TextField textField = new TextField();
VBox vbox = new VBox(label);
vbox.getChildren().add(textField);
Scene scene = new Scene(vbox);
primaryStage.setScene(scene);
primaryStage.show();
textField.focusedProperty().addListener(new ChangeListener<Boolean>()
{
#Override
public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue,
Boolean newValue)
{
// If focused
if (newValue)
{
//Need this to disable the virtual keyboard when using a textfield with scanning
//FXVK.detach();
}
}
});
}
}
Then I needed to add a wrapper class to have the virtual keyboard show up. Please note that most of the time I do use the virtual keyboard when text fields get focus, it's other times where I need to be able to programmatically disable it during certain situations.
The wrapper class:
package com.test.sampleapp.application;
import java.lang.reflect.Method;
public class AppWrapper
{
public static void main(String[] args) throws Exception
{
Class<?> app = Class.forName("com.test.sampleapp.application.Main");
Method main = app.getDeclaredMethod("main", String[].class);
System.setProperty("com.sun.javafx.isEmbedded", "true");
System.setProperty("com.sun.javafx.touch", "true");
System.setProperty("com.sun.javafx.virtualKeyboard", "javafx");
Object[] arguments = new Object[]{args};
main.invoke(null, arguments);
}
}
Let me know if you need anything else such as the build.gradle file however this is mostly just an issue using java 9 or beyond.

Answer 1

The FXVK class still exists in the same package, so the only issue is that its package is not exported by the javafx.controls module. If you must use this internal class, then you can pass an appropriate --add-exports JVM argument both at compile-time and at run-time.
Here's a simple application that calls FXVK#detach():
// Will fail at compile-time if the '--add-exports` argument is not
// passed to 'javac'
import com.sun.javafx.scene.control.skin.FXVK;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
var root = new StackPane(new Label("Hello, World!"));
primaryStage.setScene(new Scene(root, 600, 400));
primaryStage.show();
// Will fail at run-time if the '--add-exports' argument is
// not passed to 'java'
FXVK.detach();
}
}
Assuming you put the Main.java file in your working directory, you can compile it with:
javac -p <path-to-fx> --add-modules javafx.controls --add-exports javafx.controls/com.sun.javafx.scene.control.skin=ALL-UNNAMED Main.java
And run it with:
java -p <path-to-fx> --add-modules javafx.controls --add-exports javafx.controls/com.sun.javafx.scne.control.skin=ALL-UNNAMED Main
If your code is modular then you can get rid of the --add-modules and you must change ALL-UNNAMED to the name of your module. Plus, make sure to launch your application via --module (or -m). Note the -p above is shorthand for --module-path.
If you use a build tool (e.g., Maven, Gradle, etc.), then you'll have to lookup how to set these JVM arguments for that tool. You'll also have to take into account how you deploy your application. For instance, if you use jpackage then you can use its --java-options argument to set the --add-exports option for when your application is launched.
You may also need to tell your IDE that you are giving yourself access to the internal package. Otherwise, your IDE will likely yell at you for trying to use an inaccessible type.