Re: write read string data

From:
Hendrik Maryns <gtw37bn02@sneakemail.com>
Newsgroups:
comp.lang.java.help
Date:
Tue, 20 Nov 2007 17:12:13 +0100
Message-ID:
<fhv112$cjh$1@newsserv.zdv.uni-tuebingen.de>
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bH schreef:

Hi All,
 
I am attempting to write data into a file and read it
back again.
 
The error occurs with reading the data file back,
or so it would appear as the current output of that
data is merely a column of null.

import java.io.*;
 
public class Example4withIO {
  String[][] tmp_array = new String [5][5] ;
 
  public static void main(String[] args) {
    new Example4withIO();
  }
  public 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},
      };


In a more advanced application, you would create a class Person which
has these things as attributes, but I understand that this is only an
exercise.

      try {
        FileOutputStream f_out = new FileOutputStream
        ("C:\\myarray.data");
        ObjectOutputStream obj_out =
        new ObjectOutputStream (f_out);


Java naming conventions[1] would require you to write that as fOut,
objOut. Also, consider using more descriptive names.

        obj_out.writeObject(data);
        obj_out.flush();
        obj_out.close();
      }
      catch (IOException e)
      {
        System.out.println("error obj_out");


You might want to e.printStackTrace().

      }
      // end saving data
      // attempting to recover the data
      try {
        BufferedReader obj_in =
        new BufferedReader(new FileReader
        ("C:\\myarray.data"));
        tmp_array.equals (obj_in);
        obj_in.close();


You never actually read from the BufferedReader. equals is just a
method to compare objects, see the Javadoc[2].

What you need is ObjectInputStream[3] and its readObject() method.

HTH, H.

[1] http://java.sun.com/docs/codeconv/html/CodeConventions.doc8.html
[2]
<http://72.5.124.55/javase/6/docs/api/java/lang/Object.html#equals(java.l=
ang.Object)>
[3] http://72.5.124.55/javase/6/docs/api/java/io/ObjectInputStream.html
--
Hendrik Maryns
http://tcl.sfs.uni-tuebingen.de/~hendrik/
==================
http://aouw.org
Ask smart questions, get good answers:
http://www.catb.org/~esr/faqs/smart-questions.html

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