I/O using XML in Java.

Number_25 · 7 Feb 2013 at 17:08

Hey guys,

We've been asked to create a application which utalises 3 kinds of IO, text, XML and serialization.

Text and Serialization went by without any hitches, but for some reason XML refuses to work.

Quick overview of the application here.

Two classes, books and authors.
Linked by the author instance variable.
Method class with all of the methods inside (who would have guessed?)

This is what I've got.

Going to the method -

Code:

try {
                   writeXML("file.xml");
                }
                catch (IOException e) {
                    System.out.println("Error whilst writing file");
                }
            }

The method itself

Code:

public void writeXML(String fn) throws IOException {
        XMLEncoder encoder = new XMLEncoder(new BufferedOutputStream(
                new BufferedOutputStream(
                        new FileOutputStream(fn))));
        encoder.writeObject(this);
        encoder.close();
    }

I can't see anything wrong there, can you?

Edit:- Important to note that the ArrayList with the book and author objects stored is also in this class - hense the (this).

Number_25 · 7 Feb 2013 at 20:16

No error at all.

Number_25 · 7 Feb 2013 at 20:17

peterwalkley said:
What error is reported if you print the IOException out instead of suppressing it ?
Also, why use 2 BufferedOutputStream objects ?

Oh.

Two BufferedOutputStreams probably!

Number_25 · 7 Feb 2013 at 20:47

Nope.

Wasn't that.

This is what the created XML displays...

<?xml version="1.0" encoding="UTF-8"?>
<java version="1.7.0_10" class="java.beans.XMLDecoder">
<object class="Model"/>
</java>

Number_25 · 8 Feb 2013 at 10:24

They've all got both.

Number_25 · 9 Feb 2013 at 21:11

I can only do it the way I've been taught.

Number_25 · 11 Feb 2013 at 20:48

Let me show you how I've done my seriazliable, it works without any hitches whatsoever.

Code:

    public void write(String fn) throws IOException{
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(fn));
        oos.writeObject(this);
        oos.close();
    }

Number_25 · 11 Feb 2013 at 21:04

Ok, tried something different,

Now I'm getting -

java.lang.InstantiationException: Author
Continuing ...
java.lang.Exception: XMLEncoder: discarding statement ArrayList.add(Author);
Continuing ...