Working with Apache POI

import org.apache.poi.xssf.usermodel.XSSFWorkbook

val book = new XSSFWorkbook(filename)
val items = for {
  i <- 0 until book.getNumberOfSheets
  sheet = book.getSheetAt(i)
  j <- 0 until sheet.getPhysicalNumberOfRows
  row = sheet.getRow(j)
  k <- 0 until row.getPhysicalNumberOfCells
  cell = row.getCell(k)
} yield cell.getStringCellValue