private void addBoxes() {
		while(boxes.size() < nHW) {
			Box newBox = new HeavyWeight(System.currentTimeMillis());
			if( !overlaps(newBox) )
				boxes.add(newBox);
		}
		while(boxes.size() < nHW+nWH) {
			Box newBox = new WhiteHole(System.currentTimeMillis());
			if( !overlaps(newBox) )
				boxes.add(newBox);
		}
		while(boxes.size() < nHW+nWH+nLW) {
			Box newBox = new LightWeight(System.currentTimeMillis());
			if( !overlaps(newBox) )
				boxes.add(newBox);
		}
	}