My map load parser is taking ages on android

Newbie & Debugging Questions
#1

I am having some trouble with loading on android as it is taking for ever to load a 500x500 map

Okay first:
How do i make it load from another thread? I am using libgdx but I would like to know how to do it in pure java and libgdx Gdx.app.postRunnable() I want another thread so i can show the user that the game is loading with a little animation screen

second for a map size of 500 x 500 should i consider using the chunking system… if so how?

Here is my parser code

public static TileMap loadMap(FileHandle file) {
		if (!file.extension().contains("hawk")) {
			System.err.println("Wrong file");
			return new TileMap(100, 100, TileType.GRASS);
		}
		TileMap map = null;
		BufferedReader reader = new BufferedReader(new StringReader(file.readString()));

		try {
			String[] configString = reader.readLine().split(",");
			int mapWidth = Integer.parseInt(configString[0]);
			int mapHeight = Integer.parseInt(configString[1]);

			String line = null;
			int counterX = 0;
			int counterY = 0;
			
			MasterTile[][] tiles = new MasterTile[mapWidth][mapHeight];
			
			while ((line = reader.readLine()) != null) {
				String[] split = line.split(",");
				int botTile = Integer.parseInt(split[0]);
				int topTile = Integer.parseInt(split[1]);
				float rotationBot = 90;
				float rotationTop = 90;
				boolean fXBot = false;
				boolean fYBot = false;
				boolean fXTop = false;
				boolean fYTop = false;
				if(split.length > 2){
					rotationBot = Float.parseFloat(split[2]);
					rotationTop = Float.parseFloat(split[3]);
					if(split.length > 4){
					fXBot = Boolean.parseBoolean(split[4]);
					fYBot = Boolean.parseBoolean(split[5]);
					fXTop = Boolean.parseBoolean(split[6]);
					fYTop = Boolean.parseBoolean(split[7]);
					}
				}
				Tile bot = TileUtils.createTile(botTile);
				bot.setRotation(rotationBot);
				bot.setFlipX(fXBot);
				bot.setFlipY(fYBot);
				Tile top = TileUtils.createTile(topTile);
				top.setRotation(rotationTop);
				top.setFlipX(fXTop);
				top.setFlipY(fYTop);
				
				tiles[counterX][counterY] = new MasterTile(counterX*MasterTile.TILE_WIDTH, counterY*MasterTile.TILE_HEIGHT, top, bot);
				counterY++;
				if(counterY > mapHeight-1){
					counterY = 0;
					counterX++;
				}
				if(counterX > mapWidth-1){
					counterX = 0;
				}
				
			}
			
			map = new TileMap(mapWidth, mapHeight, tiles);

			reader.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		

		return map;
	}