将爪哇转换为标点码

Question

将java转换为scala代码我面临一个奇怪的问题一个例子可以在这里找到https://gist.github.com/geoHeil/895260a04d3673b9848b345edf388a2d错误是

[error] src/main/scala/myOrg/CustomInputMapperWKT.scala:17: overriding method call in trait FlatMapFunction of type (x$1: String)java.util.Iterator[Any];
[error]  method call has incompatible type
[error]   override def call(line: String): Iterator[_] = {

当试图将spark java转换为spark scala API时，我正在努力将这个java类https://html" target="_blank">github . com/DataSystemsLab/geos park/blob/master/src/main/Java/org/datasyslab/geos park/showcase/usersuppliedpolygonmapper . Java # L59-L81移植到scala。

哪里

class CustomInputMapperWKT extends FlatMapFunction[String, Any] {
....
override def call(line: String): Iterator[_] = {
val result: collection.Seq[Polygon] with Growable[Polygon] = mutable.Buffer[Polygon]()
result.iterator
  }
}

是描述问题的最小样本。

试图解决一个可能的打字问题，我用其各自的多边形类型替换了Any。但这对福克斯来说无济于事。

Answer 1

你试过这个签名吗？

override def call(t: String): java.util.Iterator[Any] = {
...

因为这个代码示例编译成功：

import org.apache.spark.api.java.function.FlatMapFunction
import collection.JavaConverters._

class CustomInputMapperWKT extends FlatMapFunction[String, Any] {
  override def call(t: String): java.util.Iterator[Any] = {
    ...
    result.iterator.asJava
  }
}