JavaFx：无法识别错误

Question

我在 JavaFx8 中创建了一个运行良好的应用程序，但有时会显示如下所述的异常。我不明白为什么我会遇到这种异常。有没有办法跟踪这个异常。或者任何熟悉这种例外的人。请帮忙。

java.lang.NullPointerException
    at com.sun.pisces.PiscesRenderer.fillLCDAlphaMask(PiscesRenderer.java:334)
    at com.sun.prism.sw.SWGraphics.drawStringInternal(SWGraphics.java:776)
    at com.sun.prism.sw.SWGraphics.drawString(SWGraphics.java:732)
    at com.sun.javafx.sg.prism.NGText.renderText(NGText.java:319)
    at com.sun.javafx.sg.prism.NGText.renderContent(NGText.java:277)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:412)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:69)
    at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1283)
    at com.sun.javafx.sg.prism.NGGroup.renderChildren(NGGroup.java:237)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:203)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:1254)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:412)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:69)
    at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1283)
    at com.sun.javafx.sg.prism.NGGroup.renderChildren(NGGroup.java:237)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:203)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:1254)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:412)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:69)
    at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1283)
    at com.sun.javafx.sg.prism.NGGroup.renderChildren(NGGroup.java:237)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:203)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:1254)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:412)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:69)
    at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1283)
    at com.sun.javafx.sg.prism.NGGroup.renderChildren(NGGroup.java:237)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:203)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:1254)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:412)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:69)
    at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1283)
    at com.sun.javafx.sg.prism.NGGroup.renderChildren(NGGroup.java:237)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:203)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:1254)
    at com.sun.javafx.sg.prism.NodeEffectInput.render(NodeEffectInput.java:154)
    at com.sun.javafx.sg.prism.NodeEffectInput.filter(NodeEffectInput.java:84)
    at com.sun.scenario.effect.Merge.filter(Merge.java:161)
    at com.sun.scenario.effect.DelegateEffect.filter(DelegateEffect.java:70)
    at com.sun.scenario.effect.impl.prism.PrEffectHelper.render(PrEffectHelper.java:164)
    at com.sun.javafx.sg.prism.NGNode$EffectFilter.render(NGNode.java:951)
    at com.sun.javafx.sg.prism.NGNode.renderEffect(NGNode.java:701)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:410)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:69)
    at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1283)
    at com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:99)
    at com.sun.javafx.tk.quantum.AbstractPainter.paintImpl(AbstractPainter.java:202)
    at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:95)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304)
    at com.sun.javafx.tk.RenderJob.run(RenderJob.java:58)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:129)
    at java.lang.Thread.run(Thread.java:724)

Answer 1

在后续版本中修复的已知问题

PiscesRendere.java 第 334 行的 NullPointerException 是一个已知错误，如果您升级到更高版本的JavaFX 8 build，应该修复它。

RT-31384 fx8.0-b96: NullPointerException in fillLCDAlphaMask in sw pipeline

在未来自行解决此类问题

1. 您可以使用latest Java 8 distribution (which includes the latest JavaFX distribution) 测试您的代码。

2. 您可以检查bug tracker 并在错误不存在时提交错误。您将需要提供更多信息，例如您的环境、重现步骤和重现错误的可执行代码示例。

3. 您可以根据 JavaFX 源代码（例如 PiscesRenderer.java source is here）自行调试问题。请注意，您需要选择正确的源标签以匹配您的构建。

4. 或者你可以build and patch JavaFX yourself。