为什么暴风雨流的明确定义不起作用，而隐含的定义却起作用呢？

Question

    StreamBuilder builder = new StreamBuilder();
    builder
        .newStream(new IntSpout(), new ValueMapper<Integer>(0), 1)
        .filter(x -> x > 5)
        .print();

    Stream<Integer> integerStream = builder.newStream(new IntSpout(), new ValueMapper<Integer>(0), 1);
    integerStream.filter(x -> x > 5);
    integerStream.print();

java prettyprint-override">    StormTopology topo = builder.build();
    LocalCluster cluster = new LocalCluster();
    cluster.submitTopology("test", new HashMap<>(), topo);

Answer 1

这是因为integerstream.filter(x->x>5)；返回一个您忽略的新流。

这是可行的：

    Stream<Integer> integerStream = builder.newStream(new IntSpout(), new ValueMapper<Integer>(0), 1);
    Stream<Integer> filteredStream = integerStream.filter(x -> x > 5);
    filteredStream.print();

在您的第一个示例中还有一个语法错误。它在第四行末尾多了一个分号。

StreamBuilder builder = new StreamBuilder();
builder
    .newStream(new IntSpout(), new ValueMapper<Integer>(0), 1)
    .filter(x -> x > 5) // <= there was a semicolon here 
    .print();