在火花 java dataframe 中合并列

Question

There are similar posts on Stack Overflow for the same question but none on a Java Spark Dataframe.

Can anyone help me with the same but in java.

I tried the solution posted here but its not working on Java. Seems like coalesce function takes Scala.collections.seq<columns> as type. how to make it work in Java

Answer 1

I had to convert the columns to Seq to make it work in Java 8.

public Seq<Column> getSeqString(Column a, Column b)
    {
        ArrayList<Column> cols = new ArrayList<Column>();
        cols.add(a);
        cols.add(b);
        return scala.collection.JavaConverters.collectionAsScalaIterableConverter(cols).asScala().toBuffer();
    }