Re: write read string data

From:

=?ISO-8859-1?Q?Roger_Lindsj=F6?= <news.nospam@tilialacus.net>

Newsgroups:

comp.lang.java.help

Date:

Wed, 21 Nov 2007 11:26:05 +0100

Message-ID:

<fi10o4$3cb$1@blue.telenor.se>

bH wrote:

On Nov 20, 11:09 pm, Roedy Green <see_webs...@mindprod.com.invalid>
wrote:

On Tue, 20 Nov 2007 07:02:20 -0800 (PST), bH <bherbs...@hotmail.com>
wrote, quoted or indirectly quoted someone who said :

I am attempting to write data into a file and read it
back again.

You have to read back with the same technique you write out with.

e.g. write objects / read objects.
write binary / read binary
write encoded chars / read encoded chars

Seehttp://mindprod.com/applet/fileio.html
for sample code to do it various ways.

You might do it each way and examine the file with a hex viewer to
understand the different formats.
--
Roedy Green Canadian Mind Products
The Java Glossaryhttp://mindprod.com

Hi All.

I am not sure, at this point, if this is what was expected.

bH

import java.io.*;

public class Example4withIO {

  public static void main(String[] args) {
    Example4withIO example4withIO =
      new Example4withIO();
    GetData getData1 = new GetData();
  }
  public Example4withIO() {
    System.out.println("inside Example4withIO");
    // final String[] names = {"First Name",
    // "Last Name", "Favorite Color",
    // "Favorite Number", "Vegetarian"};
    final Object[][] data = {
      {"Mark", "Andrews", "Red", new Integer(2),
        Boolean.TRUE},
      {"Tom", "Ball", "Blue", new Integer(99),
        Boolean.FALSE},
      {"Alan", "Chung", "Green", new Integer(838),
        Boolean.FALSE},
      {"Jeff", "Dinkins", "Turquois", new Integer(8),
        Boolean.TRUE},
      {"Amy", "Fowler", "Yellow", new Integer(3),
        Boolean.FALSE},
    };
    try {
      FileOutputStream fileOut =
        new FileOutputStream("C:\\myarray.data");
      ObjectOutputStream objOutStream =
        new ObjectOutputStream (fileOut);
      objOutStream.writeObject(data);
      objOutStream.flush();
      objOutStream.close();
    }
    catch (IOException e)
    {
      System.out.println("error getting data");
    }
  }
}

import javax.swing.*;
import java.io.*;

public class GetData extends JPanel {

  String tempStrng = new String();

  public GetData () {
    System.out.println("inside GetData");
    try {
      FileInputStream fileIn =
        new FileInputStream("C:\\myarray.data");
      ObjectInputStream objInStream =
        new ObjectInputStream(fileIn);
      tempStrng.equals(objInStream.readObject());
      if(tempStrng!= null){
        System.out.println(tempStrng); //no data
      }
      objInStream.close();
    }
    catch (Exception ee) {
      ee.printStackTrace();
    }
  }
}

I'm not sure what you are trying to do when reading the object back.
Originally you stored a Object[][], and then you compare it to a String.
The value of the comparison (true or false) is ignored and you happily
continue with checking if your string is not null. Perhaps you wanted
something like this:

import javax.swing.*;
import java.io.*;

public class GetData extends JPanel {

   Object[][] tempObj;

   public void GetData () {
     System.out.println("inside GetData");
     try {
       FileInputStream fileIn = new FileInputStream("C:\\myarray.data");
       ObjectInputStream objInStream = new ObjectInputStream(fileIn);
       tempObj = (Object[][])(objInStream.readObject());
       if(tempObj!= null){
    for (Object[] oa: tempObj) {
           for (Object o: oa) {
             System.out.print(o);
             System.out.print(" ");
           }
           System.out.println();
         }
       }
       objInStream.close();
     }
     catch (Exception ee) {
       ee.printStackTrace();
     }
   }
}

Note, I have not compiled this.

//Roger LindsjF