Java 用于scala的Android Filter searchView小部件；获得ClassCastException“；

我想在Scala插件eclipse中为android创建“searchView小部件”， 这是我的密码

 override def getFilter(): Filter = {
  new Filter() {

    protected override def publishResults(constraint: CharSequence, results: 
FilterResults) {
      var books = results.values.asInstanceOf[List[BookMetadata]]
      ItemAdapter.this.notifyDataSetChanged()
    }

    protected override def performFiltering(constraint: CharSequence): FilterResults = {

      val filteredResults = ListBuffer(books.asScala.toList.filter(b =>
        b.toString.startsWith(constraint.toString)): _*) .asInstanceOf[List[BookMetadata]]
      val results = new FilterResults()
      results.values = filteredResults
      results
    }
  }
}

我没有任何错误，但是当我运行程序时，我有这个ClassCastException

这是我的日志：

 08-23 13:37:06.986: V/BookFragment(25407): query : modern
 08-23 13:37:06.996: W/Filter(25407): An exception occured during performFiltering()!
 08-23 13:37:06.996: W/Filter(25407): java.lang.ClassCastException:  
scala.collection.mutable.ListBuffer cannot be cast to java.util.List
08-23 13:37:06.996: W/Filter(25407):    at   
com.bitlit.android.BooksFragment$ItemAdapter$$anon$2.
performFiltering(BooksFragment.scala:138)
08-23 13:37:06.996: W/Filter(25407):    at 
android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)

08-23 13:37:06.996: W/Filter(25407):    at   
android.os.Handler.dispatchMessage(Handler.java:99)

 08-23 13:37:06.996: W/Filter(25407): 
at android.os.Looper.loop(Looper.java:137)
08-23 13:37:06.996: W/Filter(25407): 
at android.os.HandlerThread.run(HandlerThread.java:61)

你能给我一些关于这个实现的提示吗

---

提前谢谢

查看跟踪，导致问题的行似乎是：

val filteredResults = ListBuffer(books.asScala.toList.filter(b =>
    b.toString.startsWith(constraint.toString)): _*) .asInstanceOf[List[BookMetadata]]

你在做这样的事情：

val filteredResults = ListBuffer(meta1, meta2).asInstanceOf[List[BookMetadata]]

import collection.JavaConverters._
val filteredResults = ListBuffer(/* ... */).asJava
// should return an instance of java.util.List

因此，

ListBuffer[bookmatadata]

不是

List[bookmatadata]

的实例。无论您是指

java.util.List

还是scala immutable

List

，情况都是如此

您可能可以这样做：

val filteredResults = ListBuffer(meta1, meta2).asInstanceOf[List[BookMetadata]]

import collection.JavaConverters._
val filteredResults = ListBuffer(/* ... */).asJava
// should return an instance of java.util.List