java - 运行文件选择器的 Scala 类

Question

当我在 Scala 中运行此代码时，它运行良好:

scala> import javax.swing.JFileChooser
scala> import java.io.File
scala> def run() {
    var chooser = new JFileChooser();
    chooser.setCurrentDirectory(new java.io.File("."));
    chooser.setDialogTitle("choosertitle");
    chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
    chooser.setAcceptAllFileFilterUsed(false);
    if (chooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
      System.out.println("getCurrentDirectory(): " + chooser.getCurrentDirectory());
      System.out.println("getSelectedFile() : " + chooser.getSelectedFile());
    } else {
      System.out.println("No Selection ");
    }
 }
scala> run()

但是这段代码不起作用，我想了解为什么:

scala> class FileChoose {
  def run() {
    var chooser = new JFileChooser();
    chooser.setCurrentDirectory(new java.io.File("."));
    chooser.setDialogTitle("choosertitle");
    chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
    chooser.setAcceptAllFileFilterUsed(false);
    if (chooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
      System.out.println("getCurrentDirectory(): " + chooser.getCurrentDirectory());
      System.out.println("getSelectedFile() : " + chooser.getSelectedFile());
    } else {
      System.out.println("No Selection ");
    }
  }
}
defined class FileChoose

问题是这样的:

scala> new FileChoose.run()
<console>:13: error: not found: value FileChoose
              new FileChoose.run()
                  ^

Answer 1

(new FileChoose).run()

如果您考虑以下示例，那么为什么需要这样就很清楚了:

class Bar {
  def foo {}
}

object Bar {
  class foo
}

new Bar.foo
(new Bar).foo