Question

启动一个应用程序并通过其他类与之交谈（在启动时尚未实例化），我想构建具有多个窗口和Thread相互交互的多应用程序。

我将用不太笼统的问题来解释我的问题。我有“ ApplicationPane”应用程序1：如何使用对象参数实例化GUI？这是问题的第一部分。通常，当我在一个项目上时，我自然会有一个前端（这里是JavaFX GUI）和一个后端（一个或一个由对象“后端”引用的线程）。

public static void main(String... args) {

    SampleDrawingProcessor sampleDrawingProcessor = new SampleDrawingProcessor();


    Oscillator os1 = new Oscillator(440, SoundProductionSystem.Waveform.SIN);

    os1.getOutProcessors().put("Drawing samples", sampleDrawingProcessor);


    ApplicationPane applicationPane = new ApplicationPane(sampleDrawingProcessor);


    os1.start();

    sampleDrawingProcessor.start();

}

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
 at be.manudahmen.mylittlesynth.processor.AudioViewer.render(AudioViewer.java:71)
 at be.manudahmen.mylittlesynth.processor.AudioViewer$CanvasRedrawTask.handle(AudioViewer.java:201)
 at javafx.animation.AnimationTimer$AnimationTimerReceiver.lambda$handle$485(AnimationTimer.java:57)
 at java.security.AccessController.doPrivileged(Native Method)
 at javafx.animation.AnimationTimer$AnimationTimerReceiver.handle(AnimationTimer.java:56)
 at com.sun.scenario.animation.AbstractMasterTimer.timePulseImpl(AbstractMasterTimer.java:357)
 at com.sun.scenario.animation.AbstractMasterTimer$MainLoop.run(AbstractMasterTimer.java:267)
 at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:514)
 at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:498)
 at com.sun.javafx.tk.quantum.QuantumToolkit.pulseFromQueue(QuantumToolkit.java:491)
 at com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$403(QuantumToolkit.java:319)
 at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
 at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
 at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
 at java.lang.Thread.run(Thread.java:748)

public static void testOscillator() {
    ApplicationPane.main();
}

public static void main(String ... args)
{
    ApplicationPane applicationPane = new ApplicationPane();

    SampleDrawingProcessor sampleDrawingProcessor = new SampleDrawingProcessor(applicationPane);

    Oscillator os1 = new Oscillator(440, SoundProductionSystem.Waveform.SIN);
    os1.getOutProcessors().put("Drawing samples", sampleDrawingProcessor);
    os1.start();

    sampleDrawingProcessor.start();
}

问题似乎是new ApplicationPane()似乎是null或开始时创建的画布是null之后的应用程序引用。

   if(app==null)
        System.exit(-1);
    Canvas drawingZone = app.
            getDrawingZone();
    if(drawingZone==null)
        System.exit(-2);
    GraphicsContext context2D = drawingZone.getGraphicsContext2D();

"C:\Program Files\Java\jdk1.8.0_171\bin\java" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2017.1.6\lib\idea_rt.jar=57668:C:\Program Files\JetBrains\IntelliJ IDEA 2017.1.6\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_171\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_171\jre\lib\rt.jar;C:\Program Files\Java\jdk1.8.0_171\lib\javafx-mx.jar;C:\Users\Win\IdeaProjects\MyLittleSynth\out\production\MyLittleSynth;C:\Users\Win\IdeaProjects\MyLittleSynth\lib\empty3-64.jar;C:\Users\Win\IdeaProjects\MyLittleSynth\lib\xuggler-3.4.jar" be.manudahmen.mylittlesynth.processor.apps.ApplicationPane

Process finished with exit code -2

    GraphicsContext context2D = drawingZone.getGraphicsContext2D();

Answer 1

嗯，我现在了解的是，无法使用new关键字创建应用程序。我在start（Stage）方法中放置了一个任务，以创建到其他线程的链接。

从另一个线程在应用程序jfx canvas中编写

1 个答案: