Scala cheatsheet

resultset-iteartor.scala

// How to convert a JDBC iterator to a Scala iterator

/* A data model to reflect the content of ResultSet */
case class Movie(mId: Int, title: String, rId: Int, ratingDate: String)

import java.sql.{ ResultSet, Statement }

val stmt: Statement = ???
val rs: ResultSet = statement.executeUpdate("SELECT * FROM movie".stripMargin)

// 1. Wrap it around a Scala iterator; it is more flexible
val itr1: Iterator[Movie] = new Iterator[Movie] {
  override def hasNext: Boolean = rs.next()

  override def next(): Movie = new Movie(rs.getInt(1), rs.getString(2), rs.getInt(3), rs.getString(4))
}

// 2. Use `continually`; it is more compact and easy
val itr2: Iterator[Movie] = 
Iterator.continually(rs).takeWhile(_.next()).map(rs => Movie(rs.getInt(1), rs.getString(2), rs.getInt(3), rs.getString(4)))