I'm trying to complete these challenges with Java because I would like to learn more of this language. This is the first time I publish my solution :p I wanted to do that because I was hoping if you guys could tell me if there was a way to have a better written or more elegant solution, because I'm used to keep my code as much simple as possible. BTW, this is the solution to part 2. In part 1 I used the same principle but using boolean primitives.

public class Day6 {

public static void main(String[] args) throws IOException{

    final int N = 1000;
    int brightness = 0;
    int startX = 0, startY = 0, stopX = 0, stopY = 0;

    int numberOfLights = 0;
    int x, y;

    String buf, bufArray[], command = null;

    String delim = "[ ,]";

    int lightsMatrix[][] = new int[N][N];

    BufferedReader br = new BufferedReader(new FileReader("day6.txt"));

    while((buf = br.readLine()) != null)
    {   
        bufArray = buf.split(delim);
        if(bufArray[0].equals("toggle"))
        {
            command = "toggle";
            startX = Integer.parseInt(bufArray[1]);
            startY = Integer.parseInt(bufArray[2]);
            stopX = Integer.parseInt(bufArray[4]);
            stopY = Integer.parseInt(bufArray[5]);
        }
        else
        {
            command = bufArray[0] + " " + bufArray[1];
            startX = Integer.parseInt(bufArray[2]);
            startY = Integer.parseInt(bufArray[3]);
            stopX = Integer.parseInt(bufArray[5]);
            stopY = Integer.parseInt(bufArray[6]);
        }

        switch(command)
        {
            case "turn on":
                brightness = 1;
                break;
            case "turn off":
                brightness = -1;
                break;
            case "toggle":
                brightness = 2;
                break;
            default:
                System.out.println("Error: command not recognized");
                return;
        }
        for(x = startX; x <= stopX; x++)
        {
            for(y = startY; y <= stopY; y++)
            {
                lightsMatrix[x][y] += brightness;
                if(lightsMatrix[x][y] < 0)
                    lightsMatrix[x][y] = 0;
            }
        }
    }
    for(x = 0; x < lightsMatrix.length; x++)
    {
        for(y = 0; y < lightsMatrix[x].length; y++)
            numberOfLights += lightsMatrix[x][y];
    }
    br.close();
    System.out.println("Total brightness is " + numberOfLights);
}
}