Scala: for loop until condition

Question

How can I run for until a condition is met? Instead of using scala.util.control.Breaks.break, is it possible to test for a condition within for?

for(line <- source.getLines) {
        if (line.equals("")) scala.util.control.Breaks.break
        Console print "Message> "
        dataWriter.write(line, InstanceHandle_t.HANDLE_NIL)
      }
    } catch  {
        case e: IOException =>{

You should use takeWhile like this: for(line <- source.getLines.takeWhile{_ != ""}) — senia
– senia, Commented Nov 25, 2013 at 7:45
Thanks @senia ! Is it safe to use != to compare Strings, instead of !equals("")? — Hanxue
– Hanxue, Commented Nov 25, 2013 at 7:54
Yes. In scala == is a null-safe equivalent of equals (it calls equals). There is another operator for reference equality (and you don't need it). — senia
– senia, Commented Nov 25, 2013 at 7:57

tiran · Accepted Answer · 2013-11-25 08:27:22Z

8

Try takeWhile

for(line <- source.getLines.takeWhile(!_.isEmpty)) {
  Console print "Message> "
  dataWriter.write(line, InstanceHandle_t.HANDLE_NIL)
}

or

source.getLines.takeWhile(!_.isEmpty).foreach {
  line => 
   Console print "Message> "
   dataWriter.write(line, InstanceHandle_t.HANDLE_NIL)
}

answered Nov 25, 2013 at 8:27

tiran

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