private void prepareMaps(final Path drumMaps) {
		final String[] files = drumMaps.toFile().list();
		if (files != null) {
			this.initState.setSize(InitState.DRUM_MAP, files.length);
			for (final String f : files) {
				if (f.startsWith("drum") && f.endsWith(".drummap.txt")) {
					final String idString = f.substring(4, f.length() - 12);
					final int id;
					try {
						id = Integer.parseInt(idString);
					} catch (final Exception e) {
						this.initState.progress();
						continue;
					}
					this.taskPool.addTask(new Runnable() {

						@Override
						public final void run() {
							try {
								copy(drumMaps.resolve(f),
										AbcCreator.this.bruteDir.resolve(f));

								AbcCreator.this.initState.progress();
							} catch (final IOException e) {
								e.printStackTrace();
							}
						}
					});
					this.maps.add(id);
				} else {
					this.initState.progress();
				}
			}
		}
		for (int i = 0; i < AbcCreator.DRUM_MAPS_COUNT; i++) {
			this.maps.add(i);
		}
		this.taskPool.waitForTasks();
	}