我尝试使用Dataset的groupByKey方法。我找不到问题所在,也找不到使用groupByKey的任何工作示例。
因此,让我指出我在解决方案中寻找的要点:
下面是我所做的:
//Inner class
public static class Bean implements Serializable {
private static final long serialVersionUID = 1L;
private String k;
private int something;
public Bean(String name, int value) {
k = name;
something = value;
}
public String getK() {return k;}
public int getSomething() {return something;}
public void setK(String k) {this.k = k;}
public void setSomething(int something) {this.something = something;}
}
//usage
List<Bean> debugData = new ArrayList<Bean>();
debugData.add(new Bean("Arnold", 18));
debugData.add(new Bean("Bob", 7));
debugData.add(new Bean("Bob", 13));
debugData.add(new Bean("Bob", 15));
debugData.add(new Bean("Alice", 27));
Dataset<Row> df = sqlContext.createDataFrame(debugData, Bean.class);
df.groupByKey(row -> {new Bean(row.getString(0), row.getInt(1));}, Encoders.bean(Bean.class)); //doesn't compile
我得到的错误是:
无法解析不明确的方法调用-集成开发环境显示有关无法显示和无法解析matching.
MapFunction的警告:我无法显示/打印的结果
https://stackoverflow.com/questions/47756167
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