public class Art {
   
   //Entities
   public static BaseBitmap[][] player;
   public static BaseBitmap[][] testDownAnimation;
   
   //Tiles
   public static BaseBitmap testTile;
   public static BaseBitmap smallTree;
   
   //Area
   public static BaseBitmap testArea;
   public static BaseBitmap testArea2;
   
   //Others
   public static BaseBitmap sprite;
   
   public static void loadAllResources(BaseScreen screen) {
      sprite = screen.load("/art/test.png");
      player = screen.cut("/art/player/player.png", 16, 16, 0, 0);
      testTile = screen.load("/art/floor/testTile.png");
      smallTree = screen.load("/art/wall/treeSmall.png");
      testDownAnimation = screen.cut("/art/player/test_walk_down_animation.png", 16, 16, 0, 0);
      
      testArea = screen.load("/area/test/testArea.png");
      testArea2 = screen.load("/area/test/testArea2.png");
   }
}

package screen;

import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;

public class BaseBitmap {
   protected int[] pixels;
   protected int width;
   protected int height;
   
   public BaseBitmap(int w, int h) {
      this.width = w;
      this.height = h;
      this.pixels = new int[w * h];
   }
   
   public BaseBitmap(int w, int h, int[] p) {
      this.width = w;
      this.height = h;
      this.pixels = p;
   }
   
   public BaseBitmap load(String filename) {
      try {
         BufferedImage image = ImageIO.read(BaseBitmap.class.getResource(filename));
         return load(image);
      }
      catch (IOException e) {
         e.printStackTrace();
      }
      return null;
   }
   
   public BaseBitmap load(BufferedImage image) {
      if (image == null) return null;
      
      int width = image.getWidth();
      int height = image.getHeight();
      
      return new BaseBitmap(width, height, image.getRGB(0, 0, width, height, null, 0, width));
   }
   
   public BaseBitmap[][] cut(String filename, int w, int h, int clipW, int clipH) {
      try {
         BufferedImage image = ImageIO.read(BaseBitmap.class.getResource(filename));
         int xTiles = (image.getWidth() - clipW) / w;
         int yTiles = (image.getHeight() - clipH) / h;
         BaseBitmap[][] results = new BaseBitmap[xTiles][yTiles];
         for (int x = 0; x < xTiles; x++) {
            for (int y = 0; y < yTiles; y++) {
               results[x][y] = new BaseBitmap(w, h);
               image.getRGB(clipW + x * w, clipH + y * h, w, h, results[x][y].pixels, 0, w);
            }
         }
         return results;
      }
      catch (IOException e) {
         e.printStackTrace();
      }
      return null;
   }
   
   public int getWidth() {
      return this.width;
   }
   
   public int getHeight() {
      return this.height;
   }
   
   public int[] getPixels() {
      return this.pixels;
   }
}

BufferedImage image = ImageIO.read(BaseBitmap.class.getResource("/test/this/folder/out.png");
//Yes, it is 3 folders deep.

         Enumeration<URL> urls = this.getClass().getClassLoader().getResources(filename);
         for (URL url = null; urls.hasMoreElements();) {
            url = urls.nextElement();
            System.out.println(url.toString());
         }