Use Scanner to compute an average of the values in a file

 
/**
 *Output:
Average is 6.2
 */

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

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

    int count = 0;
    double sum = 0.0;

    FileWriter fout = new FileWriter("test.txt");
    fout.write("2 3.4 5 6 7.4 9.1 10.5 done");
    fout.close();

    FileReader fin = new FileReader("Test.txt");

    Scanner src = new Scanner(fin);

    while (src.hasNext()) {
      if (src.hasNextDouble()) {
        sum += src.nextDouble();
        count++;
      } else {
        String str = src.next();
        if (str.equals("done"))
          break;
        else {
          System.out.println("File format error.");
          return;
        }
      }
    }

    fin.close();
    System.out.println("Average is " + sum / count);
  }
}

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Use Scanner to compute an average of the values in a file : Scanner « Development Class « Java

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