Solved

How to monitor a writeObject() method to send its progress to a JProgressBar

Posted on 2004-08-13
6
512 Views
Last Modified: 2008-03-03
The thing is I have to write an object to a stream, but the size of the object can go up to 5 mb so I would like to give some feedback to the user.

I have a JProgressBar but don't know how to figure out the progress made by the writeObject() method.

I don't know if this is possible... Maybe using Threads?
0
Comment
Question by:b_loco
  • 2
  • 2
  • 2
6 Comments
 
LVL 86

Assisted Solution

by:CEHJ
CEHJ earned 50 total points
ID: 11792661
It might be better to writeObject into a ByteArrayOutputStream and then write that. You can monitor the latter
0
 
LVL 7

Expert Comment

by:JugglerW
ID: 11792732
You may wrap your output stream in a Stream dervied from FilterOutputStream (see JDK doc) .
So you can count how many bytes are alread sent over stream.
But for the progression bar you must know beforehand how large your object is.

0
 
LVL 2

Author Comment

by:b_loco
ID: 11793261
I'm currently away from my work computer. Anyway, the code I have looks something like this:

try{
FileOutputStream fos = new FileOutputStream("t.tmp");  
ObjectOutputStream oos = new ObjectOutputStream(fos);  

oos.writeObject(1stObj);
oos.writeObject(2ndObj);  
 
oos.close();
} catch(IOException e) {
System.out.println(e.toString());
}

I'm sorry but up to now I have always avoided writing to streams byte by byte and so I don't really know how to do it.

Also, how can I get the Object's size?
0
Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

 
LVL 7

Accepted Solution

by:
JugglerW earned 200 total points
ID: 11793489
Try this. I implemented CEHJs idea to use an ByteArrayBuffer because its easier to demonstrate. But note the ByteArrayBuffer needs as much memory on your system as object you write.

===== Save as ObjectWrite.java ===========

import java.io.*;
import java.io.ByteArrayOutputStream;
import java.io.Serializable;

public class ObjectWrite implements Serializable
{
    String s1;
    String s2;
    int    i1;

    public ObjectWrite(  )
    {
        s1     = "Hello";
        s2     = "World";
        i1     = 4711;
    }

    public String toString(  )
    {
        return "s1=" + s1 + " s2=" + s2 + " i1=" + i1;
    }

    public static void main( String[] args )
    {
        try
        {
            ObjectWrite           ow = new ObjectWrite(  );

            ByteArrayOutputStream baos = new ByteArrayOutputStream(  );
            ObjectOutputStream    oos  = new ObjectOutputStream( baos );
            oos.writeObject( ow ); // Write object to ByteArrayBuffer
            oos.close(  );

            System.out.println( "Object is " + baos.size(  ) + " bytes long" );

            // Write to file
            OutputStream out = new BufferedOutputStream( new FileOutputStream( "test.dat" ) );
            out.write( baos.toByteArray(  ) ); // You could write in smaller parts to update progress bar
            out.close(  );

            // Read from file
            ObjectInputStream in = new ObjectInputStream( new FileInputStream( "test.dat" ) );
            ObjectWrite       readed = (ObjectWrite)in.readObject(  );
            System.out.println( "read: " + readed );
        }
        catch ( IOException e )
        {
            e.printStackTrace(  );
        }
        catch ( ClassNotFoundException e )
        {
            e.printStackTrace(  );
        }
    }
}

===== End as ObjectWrite.java ===========
0
 
LVL 2

Author Comment

by:b_loco
ID: 11796018
Thank you both
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 11799785
8-)
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Java had always been an easily readable and understandable language.  Some relatively recent changes in the language seem to be changing this pretty fast, and anyone that had not seen any Java code for the last 5 years will possibly have issues unde…
Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it. Define Error Message: Line Numbers: Type of Error: Break Down…
Viewers will learn about basic arrays, how to declare them, and how to use them. Introduction and definition: Declare an array and cover the syntax of declaring them: Initialize every index in the created array: Example/Features of a basic arr…

766 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question