Accessing java fx clipboard from a commandline application?

Question

This might be a stupid question from a newbie, so bear with me. Here is what I did:

import javafx.scene.input.Clipboard;
import javafx.scene.input.ClipboardContent;

import javax.sound.sampled.Clip;

public class Main {
    public static void main(String[] args) {
        final Clipboard clipboard = Clipboard.getSystemClipboard();
        final ClipboardContent content = new ClipboardContent();
        content.putHtml("<b>Some bold html</b>");
        clipboard.setContent(content);
    }
}

I got the following error:

/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/bin/java -Didea.launcher.port=7532 "-Didea.launcher.bin.path=/Applications/IntelliJ IDEA 13 CE.app/bin" -Dfile.encoding=UTF-8 -classpath "/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/lib/tools.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/htmlconverter.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_11.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Users/kaiyin/IdeaProjects/untitled8/out/production/untitled8:/Applications/IntelliJ IDEA 13 CE.app/lib/idea_rt.jar" com.intellij.rt.execution.application.AppMain com.company.Main
Picked up _JAVA_OPTIONS: -Dawt.useSystemAAFontSettings=lcd                       -Dsun.java2d.xrender=true
Exception in thread "main" java.lang.IllegalStateException: This operation is permitted on the event thread only; currentThread = main
    at com.sun.glass.ui.Application.checkEventThread(Application.java:432)
    at com.sun.glass.ui.ClipboardAssistance.<init>(ClipboardAssistance.java:40)
    at com.sun.javafx.tk.quantum.QuantumToolkit.getSystemClipboard(QuantumToolkit.java:1127)
    at javafx.scene.input.Clipboard.getSystemClipboardImpl(Clipboard.java:410)
    at javafx.scene.input.Clipboard.getSystemClipboard(Clipboard.java:175)
    at com.company.Main.main(Main.java:10)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

Process finished with exit code 1

Is it possible to access javafx cliboard without creating a gui at all?

Answer 1

I'll ignore the question of why you would ever want to do this...

As pointed out in the comments, you need to start the FX Application Thread in order to access the JavaFX clipboard. However, you don't actually need to show a Stage at any point.

The following compiles and runs:

import javafx.application.Application;
import javafx.application.Platform;
import javafx.scene.input.Clipboard;
import javafx.scene.input.ClipboardContent;
import javafx.stage.Stage;

public class ClipboardTest extends Application {

    @Override
    public void start(Stage primaryStage) {
        final Clipboard clipboard = Clipboard.getSystemClipboard();
        final ClipboardContent content = new ClipboardContent();
        content.putHtml("<b>Some bold html</b>");
        clipboard.setContent(content);

        Platform.exit();
    }

    public static void main(String[] args) {
        launch(args);
    }
}