从继承的受保护Java字段创建公共访问器 [英] Making a public accessor from an inherited protected Java field

问题描述

如何进行以下工作：

class Foo extends javax.swing.undo.UndoManager {
  // increase visibility - works for method
  override def editToBeUndone: javax.swing.undo.UndoableEdit = super.editToBeUndone

  // fails for field
  def edits: java.util.Vector[javax.swing.undo.UndoableEdit] = super.edits
}

注意编辑是 CompoundEdit 中的受保护字段（超级 UndoManager ）。我想要一个具有相同名称的公共访问器来读取该字段。我该怎么做？

Note that edits is a protected field in CompoundEdit (a super class of UndoManager). I would like to have a public accessor with the same name that reads that field. How would I do that?

<console>:8: error: super may be not be used on variable edits
         def edits: java.util.Vector[javax.swing.undo.UndoableEdit] = super.edits
                                                                            ^

推荐答案

好吧，总会有反思。

class Foo extends javax.swing.undo.UndoManager {
  def edits(): java.util.Vector[javax.swing.undo.UndoableEdit] =
    classOf[javax.swing.undo.CompoundEdit].
    getDeclaredField("edits").get(this).
    asInstanceOf[java.util.Vector[javax.swing.undo.UndoableEdit]]
}

你也可以通过嵌套消除两个调用的歧义，虽然这很难看：

You can also disambiguate the two calls by nesting, though this is ugly:

class PreFoo extends javax.swing.undo.UndoManager {
  protected def editz = edits
}
class RealFoo extends PreFoo {
  def edits() = editz
}

你确实需要（） - 没有它与字段本身（并且您不能使用 def 覆盖 val ）。

You do need the (), though--without it conflicts with the field itself (and you can't override a val with a def).

这篇关于从继承的受保护Java字段创建公共访问器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！