我刚开始使用apache flink。我从apachekafka源代码读取数据，需要转换 DataStream .
在最后一步中，我尝试应用 WindowFunction :

DataStream<Tuple8<Double, Double, String, Double, Double, Double, Double, Double>> dataStream = 
                     env
                    .addSource(new FlinkKafkaConsumer08<>(
                                    parameterTool.getRequired("topic"),
                                    new SimpleStringSchema(), 
                                    parameterTool.getProperties()))
                    .flatMap(new SplitIntoRecordsString())
                    .flatMap(new SplitIntoTuples())
                    .keyBy(1)
                    .countWindow(5)
                    .apply(new windowApplyFunction());

    public class windowApplyFunction implements WindowFunction<
                                                            Tuple8<Double, Double, String, Double, Double, Double, Double, Double>, 
                                                            String,  
                                                            Double, 
                                                            Window>{

    public void apply(Double key, Window window,
            Iterable<Tuple8<Double, Double, String, Double, Double, Double, Double, Double>> values,
            Collector<String> out)
            throws Exception {      
        out.collect("MyResult");
    }
}

不幸的是，我遇到了以下错误，不知道如何修复它：

The method apply(WindowFunction<Tuple8<Double,Double,String,Double,Double,Double,Double,Double>,R,Tuple,GlobalWindow>) in the type WindowedStream<Tuple8<Double,Double,String,Double,Double,Double,Double,Double>,Tuple,GlobalWindow> is not applicable for the arguments (FlinkManager.windowApplyFunction)

如果我换新的，一切正常 apply(new windowApplyFunction()) 具有预定义的功能，例如。 sum(1) .