Strange error comparing strings

[Sankha Narayan Guria]

Hi,
    I have the following code segment

var reader = new BufferedReader(new InputStreamReader(new FileInputStream("file.txt")))
var line:String = null
while(!((line = reader readLine) == "")) {
  // my code here
}

In Eclipse while editing the code the editor is showing an error that comparing Unit and java.lang.String  using ' == ' will always yield false. Why is it so? I am comparing 2 String objects only. How come Unit is coming in?

Thanks,
Sankha Narayan Guria

[Rex Kerr]

Assignments return unit, not the value that was assigned.

Change that to
  { line = reader readLine; line } == ""
and it should compile (and possibly even do what you want).

  --Rex

[Ken Scambler]

Assignment always returns Unit; you can't use this idiom in Scala.  Most style guides in Java, C++, etc would discourage assignment within if/while conditions anyway.