flink 文档中给出的代码无法编译

Question

我对 flink 很陌生，正在尝试 flink 文档中给出的一些代码。

flink 文档中的代码：

public class WordWithCount {

    public String word;
    public long count;

    public WordWithCount() {}

    public WordWithCount(String word, int count) {
        this.word = word;
        this.count = count;
    }
}

DataStream<Tuple2<String, Long>> wordCounts = env.fromElements(
    new WordWithCount("hello", 1),
    new WordWithCount("world", 2));

wordCounts.keyBy("word"); // key by field expression "word"

但我在

处收到类型不匹配错误

DataStream<Tuple2<String, Long>> wicstream = sev.fromElements(new WordwithCount("Hello",1), new WordwithCount("hello",1)); 

错误信息：

Type mismatch: cannot convert from DataStreamSource<WordwithCount> to DataStream<Tuple2<String,Long>>

请帮助我理解我的错误。

Answer 1

DataStream 应该是 X 类型，与您提供给 fromElements() 方法的对象类型相同。您提供WordwithCount 作为参数，所以DataStream 的类型应该是WordwithCount。

您的代码应如下所示：

DataStream<WordwithCount> wicstream = sev.fromElements(new WordwithCount("Hello",1), new WordwithCount("hello",1));