Scala public methods: ';' expected but 'def' found

Question

I wrote this method:

public def getXScaleFactor(panelWidth: Int): Double = {
  return (panelWidth / (samplesContainer[0].length.asInstanceOf[Double]))
}

and I have problems with compilation:

[error] ./src/main/scala/Controllers/TrackController.scala:85: ';' expected but 'def' found.
[error]   public def getXScaleFactor(panelWidth: Int): Double {
[error]          ^

What is wrong in this code?

Rex Kerr · Accepted Answer · 2011-06-03T18:08:07.517

24

public is not a reserved word in Scala, so it's interpreting it as a variable name. Public access is the default; just leave off public and you'll be fine.

edited Jun 03 '11 at 18:08

answered Jun 03 '11 at 17:54

Rex Kerr

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score 5 · Answer 2 · answered Jun 03 '11 at 17:53

5

Methods are public by default. Remove public.

answered Jun 03 '11 at 17:53

Landon Kuhn

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Thanks! I thought it is optional, now I see it is not allowed at all. – ciembor Jun 03 '11 at 17:56

JaimeJorge · Answer 3 · 2011-06-03T18:19:58.343

4

Just to add up to the answers above:

You can also remove return keyword. The last statement/expression in a function/method is automatically the return value.

edited Jun 03 '11 at 18:19

answered Jun 03 '11 at 18:13

JaimeJorge

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Kevin Wright · Answer 4 · 2011-06-03T18:47:29.387

4

The problem is that you've written Java code.

As well as public, you've also used [] for indexed access to a collection (which is invalid), an explicit return type (which isn't needed), return (which also isn't needed), and .asInstanceOf (which is unnecessary, and a code smell)

Try this for a lightweight, more idiomatic experience:

def xScaleFactor(panelWidth: Int) =
  panelWidth / samplesContainer.head.length.toDouble

Or if samplesContainer might be empty:

def xScaleFactor(panelWidth: Int) =
  panelWidth / samplesContainer.headOption.map(_.length.toDouble).getOrElse(42.0)

Put whatever you prefer in place of the default 42 there

edited Jun 03 '11 at 18:47

answered Jun 03 '11 at 18:17

Kevin Wright

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+1 for thorough proofreading. Nothing wrong with `samplesContainer(0).length.toDouble`, though, depending on what `samplesContainer` is--an array, I'm guessing, and I wouldn't call using `head` on an array idiomatic. – Rex Kerr Jun 03 '11 at 20:22
Being unspecified, I'd be remiss to assume an array here, and so have to consider the most general possibility for an index-acessible collection type. `Seq` in this case. – Kevin Wright Jun 03 '11 at 21:19

Scala public methods: ';' expected but 'def' found

4 Answers4