Scala with LibGDX outputs error when creating Animation

Question

I am starting programming with Scala and I decided to make a really simple game using libgdx. I have created this class:

import com.badlogic.gdx.graphics.g2d.SpriteBatch
import com.badlogic.gdx.graphics.{GL20, Texture}
import com.badlogic.gdx.Gdx
import com.badlogic.gdx
import com.badlogic.gdx.graphics.g2d.Animation
import com.badlogic.gdx.graphics.g2d.TextureRegion


class Game extends gdx.Game {
  var batch: SpriteBatch = _
  var walkSheet: Texture = _
  var walkAnimation: Animation[TextureRegion] =  _
  var reg: TextureRegion = _
  var stateTime: Float = _


  def create(): Unit = {
    batch = new SpriteBatch()
    walkSheet = new Texture(Gdx.files.internal("assets/animations/slam with VFX.png"))
    val frames: Array[TextureRegion] = TextureRegion.split(walkSheet, walkSheet.getWidth / 1, walkSheet.getHeight / 10).flatMap(_.toList)
    walkAnimation = new Animation(1f/4f, frames)
  }

  override def render(): Unit = {
    Gdx.gl.glClearColor(1f,1f,1f,1f)
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT)

    batch.begin()
    stateTime += Gdx.graphics.getDeltaTime()
    //println(stateTime)
    reg = walkAnimation.getKeyFrame(stateTime, true)
    batch.draw(reg, 0,0,reg.getRegionWidth*4, reg.getRegionHeight*4)
    batch.end()
  }
}

(sorry for the crappines, I am just trying things right now)

As you can see, frames' type is Array[TextureRegion]. In the documentation for the libgdx Animation Class I can see that I should be able to call the constructor of Animation with this type, but intellij outputs:

[...]\git\master\src\Main\scala\Game.scala:21:42
type mismatch;
 found   : Array[com.badlogic.gdx.graphics.g2d.TextureRegion]
 required: com.badlogic.gdx.graphics.g2d.TextureRegion
    walkAnimation = new Animation(1f/4f, frames)

I have no idea what is going on. To my (limited) understandig it seems that it is trying to use a different overload of the constructor, but I do not know why neither how to solve it.

Answer 1

Yes, Scala compiler is quite confused here, because the constructor want a gdx array, not a Java array (look at the documentation). A possible workaround could be in using var arg syntax:

walkAnimation = new Animation(1f/4f, frames:_*)

In this way, it selects this constructor:

Animation(float frameDuration, T... keyFrames)

Or, if you prefer, you could use the GDX array class directly as:

import com.badlogic.gdx.utils.{Array => GDXArray}
val frames: GDXArray[TextureRegion] = new GDXArray(TextureRegion.split(walkSheet, walkSheet.getWidth / 1, walkSheet.getHeight / 10).flatMap(_.toList))
walkAnimation = new Animation(1f/4f, frames)