Writing data to a sequential text file with class Formatter. - Java File Path IO

Java examples for File Path IO:Text File

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Description

Writing data to a sequential text file with class Formatter.

Demo Code

import java.io.FileNotFoundException;
import java.util.Formatter;
import java.util.FormatterClosedException;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class Main {
  private static Formatter output; // outputs text to a file

  public static void main(String[] args) {
    openFile();/*www. j  av a 2  s . c  o m*/
    addRecords();
    closeFile();
  }

  // open file clients.txt
  public static void openFile() {
    try {
      output = new Formatter("clients.txt"); // open the file
    } catch (SecurityException securityException) {
      System.err.println("Write permission denied. Terminating.");
      System.exit(1); // terminate the program
    } catch (FileNotFoundException fileNotFoundException) {
      System.err.println("Error opening file. Terminating.");
      System.exit(1); // terminate the program
    }
  }

  // add records to file
  public static void addRecords() {
    Scanner input = new Scanner(System.in);
    System.out.printf("%s%n%s%n? ",
        "Enter account number, first name, last name and balance.",
        "Enter end-of-file indicator to end input.");

    while (input.hasNext()) // loop until end-of-file indicator
    {
      try {
        // output new record to file; assumes valid input
        output.format("%d %s %s %.2f%n", input.nextInt(), input.next(),
            input.next(), input.nextDouble());
      } catch (FormatterClosedException formatterClosedException) {
        System.err.println("Error writing to file. Terminating.");
        break;
      } catch (NoSuchElementException elementException) {
        System.err.println("Invalid input. Please try again.");
        input.nextLine(); // discard input so user can try again
      }

      System.out.print("? ");
    }
  }

  // close file
  public static void closeFile() {
    if (output != null)
      output.close();
  }
}

Result


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