Getting the average of a set of numbers, confused by file IO, please help!

Question

What i need to do is get the average of a set of numbers, the problem is that i am reading these numbers in from files in different directories where each file returns a number, and the average for the directory is the numbers for each file in that directory added together and divided by the number of files in that directory.
public static HashMap readDir(File path, HashMap map) throws IOException{
        File files[] = path.listFiles();
        float totalForDirectory = 0;
         int common = 0;
         int count = 0;
                if(files != null && files.length > 0) {
                          for(int i=0; i<files.length; i++) {
                                if(files.isDirectory()) {
readDir(files[i], map);
} else {
//trying to count the number of files in the directory
count++;
totalForDirectory =(total(common, totalF1(), totalF2(files[i])));
readFile(files[i]);
//will contain pathname, and the average
map.put(path.getCanonicalPath(), totalForDirectory);
return map;
In the above code, totalForDirectory contains the number for each file, i want to add together the result of this variable for each file, "file[i]" in the directory, and divide that by the number of files in that directory.
Id appreciate any help
Thanks

Answer 1

What you want, It seems to me, is a recursive routine (for directories) which returns both a total and a filecount. Then these can be totalled at each level (togther with the count for each file).
Probably the best approach is to pass a small object in which the totals are accumulated.
Define a class something like:
public class Accumulator {
   int count;
   int total;
   public double mean() {
      return total / count;
  public void add(Accumulator add) {
     count += add.count;
     total += add.total;
   public void add(int numberFromFile) {
      count++;
     total += numberFromFile();
  }Create an instance of this at the start of your scan directory method, and pass it when you call make the recursion. At the end of the scan the method would use the first add method to add it's local totals to the hight level total.
Obviously you create an Accumulator for the first scan directory call which becomes the grand total.