public class TestConsole1 {
  public static void main(String[] args) {
    String str = readDataFromConsole("Please input string：);
    System.out.println("The information from console： + str);
  }

  /**
   * Use InputStreamReader and System.in to read data from console
   * 
   * @param prompt
   *      
   * @return input string
   */
  private static String readDataFromConsole(String prompt) {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String str = null;
    try {
      System.out.print(prompt);
      str = br.readLine();

    } catch (IOException e) {
      e.printStackTrace();
    }
    return str;
  }
}

public class TestConsole2 {
  public static void main(String[] args) {
    String str = readDataFromConsole("Please input string:");
    System.out.println("The information from console:" + str);
  }

  /**
   * Use java.util.Scanner to read data from console
   * 
   * @param prompt
   * 
   * @return input string
   */
  private static String readDataFromConsole(String prompt) {
    Scanner scanner = new Scanner(System.in);
    System.out.print(prompt);
    return scanner.nextLine();
  }
}

public class TestConsole4 {

  public static void main(String[] args) throws IOException {
    FileWriter fw = new FileWriter("num.txt");
    fw.write("2 2.2 3.3 3.33 4.5 done");
    fw.close();

    System.out.println("Sum is "+scanFileForSum("num.txt"));
  }

  public static double scanFileForSum(String fileName) throws IOException {
    double sum = 0.0;
    FileReader fr = null;
    try {
      fr = new FileReader(fileName);
      Scanner scanner = new Scanner(fr);
      
      while (scanner.hasNext()) {
        if (scanner.hasNextDouble()) {
          sum = sum + scanner.nextDouble();

        } else {
          String str = scanner.next();

          if (str.equals("done")) {
            break;
          } else {
            throw new RuntimeException("File Format is wrong!");
          }

        }
      }

    } catch (FileNotFoundException e) {
      throw new RuntimeException("File " + fileName + " not found!");
    } finally {
      if (fr != null)
        fr.close();
    }
    return sum;
  }
}