TileFactory.java

package logic;

import java.lang.reflect.InvocationTargetException;
import java.util.HashSet;

public class TileFactory<T extends AbstractTile> {
	private TilesSet<T> tiles;
	private Class<T> clazz;
	
	public TileFactory(Class<T> clazz) {
		tiles = new TilesSet<T>();
		this.clazz = clazz;
	}
	public T getTile(int x, int y, int zoom) throws IllegalArgumentException, SecurityException, InstantiationException, IllegalAccessException, InvocationTargetException, NoSuchMethodException {
		T candidate = tiles.get(x, y, zoom);
		if(candidate == null) {
			candidate = clazz.getConstructor(new Class[]{int.class, int.class, int.class}).newInstance(x,y,zoom);
			tiles.add(candidate);
		}
		return candidate;
	}
	
	private class TilesSet<T extends AbstractTile> extends HashSet<T> {
		public T get(int x, int y, int zoom) {
			for(T current : this)
				if(current.x == x && current.y == y && current.zoom == zoom)
					return current;
			return null;
		}
	}

}