我在 scala 中使用级联 2.0,遇到了一个奇怪的编译问题
这是代码的主要部分
val sojSource = createSojSource(optionMap("input"))
val sinkScheme = createSojScheme(true)
val sink = new Hfs(sinkScheme, optionMap("output"), SinkMode.REPLACE)
var pipe = new Pipe("soj")
val each = new Each(pipe, new SojSampleFilter())
val flowDef = new FlowDef().addSource(pipe, sojSource).addTailSink(each, sink)// compile error
这是最后一行代码的错误消息
type mismatch; found : cascading.tap.hadoop.Hfs required: cascading.tap.Tap[_, _, _]
Note: org.apache.hadoop.mapred.JobConf <: Any (and cascading.tap.hadoop.Hfs <: cascading.tap.Tap[org.apache.hadoop.mapred.JobConf,org.apache.hadoop.mapred.RecordReader,org.apache.hadoop.mapred.OutputCollector]), but Java-defined class Tap is invariant in type Config. You may wish to investigate a wildcard type such as `_ <: Any`. (SLS 3.2.10)
Note: org.apache.hadoop.mapred.RecordReader <: Any (and cascading.tap.hadoop.Hfs <: cascading.tap.Tap[org.apache.hadoop.mapred.JobConf,org.apache.hadoop.mapred.RecordReader,org.apache.hadoop.mapred.OutputCollector]), but Java-defined class Tap is invariant in type Input. You may wish to investigate a wildcard type such as `_ <: Any`. (SLS 3.2.10)
Note: org.apache.hadoop.mapred.OutputCollector <: Any (and cascading.tap.hadoop.Hfs <: cascading.tap.Tap[org.apache.hadoop.mapred.JobConf,org.apache.hadoop.mapred.RecordReader,org.apache.hadoop.mapred.OutputCollector]), but Java-defined class Tap is invariant in type Output. You may wish to investigate a wildcard type such as `_ <: Any`. (SLS 3.2.10)
请你告诉我如何解决这个问题以及原因是什么?