Factory method usage, creating the correct Image subclass

Question

Hi, I created a factory method
  public enum ImgType {
    SINGLE, STRIP, SPRITE_SHEET
public static Image createImage(ImgType imgType) {
    switch (imgType) {
      case SINGLE:
        return new MyImage1(0, 0);
      case SPRITE_SHEET:
        return new MyImage2("", 0, 0);
      case STRIP:
        return new MyImage3("", 0, 0);
      default:
        throw new IllegalArgumentException("The image type " + imgType + " is not recognized.");
  }that creates different images based on the enum type provided.
and heres is a usage of that function
  public BufferedImage loadAwtImage(ImageInputStream in, String imgName,  ImageTypeFactory.ImgType imgType) throws IOException {
    BufferedImage img = imgLoader.loadImage(in);
    BufferedImage imgsubType = ImageTypeFactory.createImage(imgType);  // Convert to real Image type
    addAwtImg(imgName, imgsubType);
    return imgsubType;
  }In a test:
imgLib.loadAwtImage(imageStream, "cursor", ImageTypeFactory.ImgType.SPRITE_SHEET);Is it 'good' that in the test I can say(using the imgType enum) what sort of Image should be returned?
doesn't this expose the working of the class to the outside, on the other hand I don't know howto create the correct sub image based on an image loaded.
I use subImages to allow selection within the image, like the 3th 'tile' within an imageStrip returns just that cropped image.
Before I had List<Image> and List<List<Image>> and now I can just return Images in 1 method instead of 2,3 by using lists.
Edited by: stef569 on Dec 12, 2008 11:05 AM

Answer 1

creates specifications... :p
*  load the BufferedImage from the ImageInputStream
* add it to the cache keyed by the imgName
* @return a BufferedImage, or a custom subclass based on the imgType
* @throws IOException when the img could not be loaded
public BufferedImage loadAwtImage(ImageInputStream in, String imgName,  ImageTypeFactory.ImgType imgType) throws IOException I can test it, but the ImageTypeFactory.ImgType imgType parameter looks wrong to me.
if you see this in a class method would you change it/find a better way.