2019独角兽企业重金招聘Python工程师标准>>> 
代码
class TimeoutStateFunction extends ProcessFunction[ObjectNode, (String, Long)] {
lazy val state : ListState[CountWithTimestamp] = getRuntimeContext
.getListState(new ListStateDescriptor[CountWithTimestamp]("myState", classOf[CountWithTimestamp]))
override def processElement(value: ObjectNode, ctx: Context, out: Collector[(String, Long)]): Unit = {
//Stuff here
}
override def onTimer(timestamp: Long, ctx: OnTimerContext, out: Collector[(String, Long)]): Unit = {
//More Stuff here
}
}错误：
Error:(8, 7) class TimeoutStateFunction needs to be abstract, since method processElement in class ProcessFunction of type (x$1: com.fasterxml.jackson.databind.node.ObjectNode, x$2: org.apache.flink.streaming.api.functions.ProcessFunction[com.fasterxml.jackson.databind.node.ObjectNode,(String, Long)]#Context, x$3: org.apache.flink.util.Collector[(String, Long)])Unit is not defined
class TimeoutStateFunction extends ProcessFunction[ObjectNode, (String, Long)] {
Error:(17, 18) method processElement overrides nothing.
Note: the super classes of class TimeoutStateFunction contain the following, non final members named processElement:
def processElement(x$1: com.fasterxml.jackson.databind.node.ObjectNode,x$2: org.apache.flink.streaming.api.functions.ProcessFunction[com.fasterxml.jackson.databind.node.ObjectNode,(String, Long)]#Context,x$3: org.apache.flink.util.Collector[(String, Long)]): Unit
override def processElement(value: ObjectNode, ctx: Context, out: Collector[(String, Long)]): Unit = {
Error:(36, 16) method onTimer overrides nothing.
Note: the super classes of class TimeoutStateFunction contain the following, non final members named onTimer:
def onTimer(x$1: Long,x$2: org.apache.flink.streaming.api.functions.ProcessFunction[com.fasterxml.jackson.databind.node.ObjectNode,(String, Long)]#OnTimerContext,x$3: org.apache.flink.util.Collector[(String, Long)]): Unit
override def onTimer(timestamp: Long, ctx: OnTimerContext, out: Collector[(String, Long)]): Unit = {
原因：
Context 和 OnTimerContext 要指明为ProcessFunction内部的
解决方法：
override def processElement(
value: ObjectNode,
ctx: ProcessFunction[ObjectNode, (String, Long)]#Context,
out: Collector[(String, Long)])
: Unit = {
//Stuff here
}
override def onTimer(
timestamp: Long,
ctx: ProcessFunction[ObjectNode, (String, Long)]#OnTimerContext,
out: Collector[(String, Long)])
: Unit = {
//More Stuff here
}