OverallMean.java

import java.util.*;
import java.io.*;

public class OverallMean
{
  public static void main(String[] args) {
    File dirName = new File(args[0]);
    File[] directoryListing = dirName.listFiles();
    double total = 0;
    double numFiles = 0;
    if (directoryListing != null) {
      for (File f : directoryListing) {
        try {
          FileInputStream fin = new FileInputStream(f);
          BufferedReader infile = new BufferedReader(new
                                                      InputStreamReader(fin));
          String nLine = infile.readLine();
          nLine = infile.readLine();
          while (nLine != null) {
            String[] data = nLine.split(",");
            total += Integer.parseInt(data[1]);
            numFiles++;
            nLine = infile.readLine();
          }
          infile.close();
        } catch (IOException e) {
            System.out.println("Error reading file");
        }
      }
    }
    System.out.println("Overall Mean = " + total/numFiles);
  }
}