如何找到文件中的行数和不同元素并将它们写入header，Scala

Question

我有类似的东西：

object Example_01_IO {

  val s = Source.fromFile("example_01.txt")
  val source = s.getLines()
  val destination = new PrintWriter(new File("des_example_01.txt"))

  var nrVariables: Int = 0
  var nrLines: Int = 0

  // here are the extracted lines from example_01 that fulfills some conditions.
  val linesToWrite: Iterator[String] = ... 

  def main(args: Array[String]): Unit = {

    //Here is the header that I want to write in a destination file
    destination.write("des_example_01.txt \n")
    destination.write("Nr. of Variables and Lines: " + nrVariables + " " + nrLines + "\n")

    for(line <- linesToWrite) {
      println(line)
      destination.write(line)
      destination.write("\n")
      nrLines += 1
    }

    s.close()
    destination.close()

  }

我需要将 nrVariables 和 nrLines 的值写入目标文件的 header（例如，在第二行）。有没有可能在开始写其他行之前计算这两个值？

非常欢迎任何帮助或参考。谢谢。

Answer 1

好吧，Source.fromFile 不能重复使用，下面那个可以用：

package example

import java.io.PrintWriter
import scala.io.Source
import java.io.File

object Example_01_IO {

  def s = Source.fromFile("/tmp/example_01.txt") // notice def everywhere, looks like Source.fromFile could not be reused :(
  def source = s.getLines() 
  val destination = new PrintWriter(new File("/tmp/des_example_01.txt"))

  var nrVariables: Int = 0
  var nrLines: Int = 0

  // here are the extracted lines from example_01 that fulfills some conditions.
  def linesToWrite: Iterator[String] = source.filter { s => s.contains("a") } 

  def main(args: Array[String]): Unit = {

    linesToWrite.foreach { s =>  
      nrLines += 1
      if (s contains "variable") {
        nrVariables += 1
      }
    }


    //Here is the header that I want to write in a destination file
    destination.write("des_example_01.txt \n")
    destination.write("Nr. of Variables and Lines: " + nrVariables + " " + nrLines + "\n")

    for(line <- linesToWrite) {
      println(line)
      destination.write(line)
      destination.write("\n")
      /*nrLines += 1*/
    }

    s.close()
    destination.close()

  }
  }

如何找到文件中的行数和不同元素并将它们写入header，Scala

How to find the number of lines and different elements in a file and writing them on header, Scala

scala

file

file-writing