java - 文件选择器中的 NPE

Question

我正在尝试在 Windows 7 下运行一些 javafx 应用程序。它在 archlinux 下运行良好。

我按以下方式打开文件选择器对话框:

  @Override
  public void start(final Stage primaryStage) {
    FileChooser fileChooser = new FileChooser();
    fileChooser.setInitialDirectory(myInitialDir);
    FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("Wav files (*.wav)", "*.wav");
    fileChooser.getExtensionFilters().add(extFilter);
    File file = fileChooser.showOpenDialog(primaryStage);
  }

我上面提到的 - 在 linux 下一切正常，但在 windows 下我得到奇怪的 NPE:

Error:80070057 in SHCreateItemFromParsingName((PCWSTR)folder, NULL, IID_IShellItem, (void **)&pItem)
COM Error:80070057 0@0.
Error:80004005 in pOpenDialog->GetResults(&pFiles)
COM Error:80004005 5>?>7=0==0O >H81:0
java.lang.NullPointerException
    at com.sun.glass.ui.CommonDialogs.showFileChooser(CommonDialogs.java:120)
    at com.sun.javafx.tk.quantum.QuantumToolkit.showFileChooser(QuantumToolkit.java:1486)
    at javafx.stage.FileChooser.showDialog(FileChooser.java:285)
    at javafx.stage.FileChooser.showOpenDialog(FileChooser.java:234)
    at ru.gkalabin.diploma.gui.equalizer.EqualizerDemo$1.handle(EqualizerDemo.java:107)

有什么办法可以解决这个问题吗？

Answer 1

这是个问题:

RT-21999 Win: FileChooser does not accept valid initial directory

问题影响版本:2.2；修复版本:Lombard，因此修复在 JFX8(在 JDK8 中)中可用。

要解决此问题，请调用 <fileName>.getCanonicalPath()用于初始文件夹。

---

来自开发者的评论:

This issue is Windows 7-specific. It's not reproducible on older versions of Windows.

A workaround is to pass an absolute path as an initial directory for the file chooser (see File.getAbsolutePath()/getCanonicalPath()).

来自用户的评论:

Jason Winnebeck added a comment - Mar, 18 2013 04:30 PM I've encountered this as well, with the exact same COM errors printed to stderr, resuling in NullPointerException. I actually tried getAbsolutePath at first, but that doesn't work for all paths, for some you have to use getCanonicalPath, thankfully I found this ticket that gave me that workaround. So, I don't have much additional information to offer, except here is some groovy code that reproduces it:

public void openFile() throws IOException {
  FileChooser chooser = new FileChooser()
  chooser.title = "Select FXML"
  chooser.setInitialDirectory( new File( "." ) );
  chooser.extensionFilters.add( new FileChooser.ExtensionFilter( 
    "FXML or SVG Files",
    ["*.fxml", "*.svg"] 
  ))

  Window window = sceneProperty.get().window
  File selected = chooser.showOpenDialog( window )
}

无论其他设置如何(扩展过滤器、使用哪个窗口或为空)都会发生错误。使用 new File( "." ).canonicalFile解决了这个问题，所以根据其他报告，似乎有 .和 ..在路径中是可能的原因。