Java 弗林克加入到这条小溪中来，使它富起来

我对阿帕奇·弗林克很陌生。我使用的是v1.9.0。我想加入多个流。运行以下示例时，我遇到以下异常

例外情况：

我的主要方法是：

public class ProcessingTimeJoinExercise {

@SuppressWarnings("serial")
public static void main(String[] args) throws Exception {
    StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

    // Simulated trade stream
    DataStream<Trade> tradeStream = FinSources.tradeSource(env);

    // Simulated customer stream
    DataStream<Customer> customerStream = FinSources.customerSource(env);

    // Stream of enriched trades
    DataStream<EnrichedTrade> joinedStream = tradeStream
            .join(customerStream).where(new KeySelector<Trade, Long>() {
                @Override
                public Long getKey(Trade trade) throws Exception {
                    return trade.customerId;
                }
            }).equalTo(new KeySelector<Customer, Long>() {
                @Override
                public Long getKey(Customer cust) throws Exception {
                    // TODO Auto-generated method stub
                    return cust.customerId;
                }
            }).window(SlidingEventTimeWindows.of(Time.milliseconds(2) /* size */, Time.milliseconds(1) /* slide */))
            .apply(new JoinFunction<Trade, Customer, EnrichedTrade>() {
                @Override
                public EnrichedTrade join(Trade trade, Customer customer) {
                    return new EnrichedTrade(trade, customer);
                }
            });

    joinedStream.print();

    env.execute("processing-time join");

你知道我做错了什么吗？

如果你加上

env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);

在env初始化之后的最开始处，它将正确运行。

如果您添加

env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);

接近开始时，在env初始化之后，它将正确运行