write records to a file

[Jay Brass]

Can someone fill me in on how to write records to a file?
I have this code

try{
System.out.println("Input Date:");
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String date,dialogue;
date = br.readLine() + ".jay";//read input from the screen
System.out.println("Input Dialogue:");
OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream(date));
dialogue = br.readLine();
PrintWriter pw = new PrintWriter(new BufferedWriter(osw),true);//chaining
            pw.println(dialogue);//print the input to the file
br.close();//close the reader
osw.close();//close the output stream
}catch(IOException ioe) {System.err.println("Error in input: " + ioe);}

that writes fine to a file. But I want more than one piece of info in this file. Do I have to create a record class?
Thanks
J

[Ashwin Desai]

Hi,
There are a few ways of writing data to a file. It really depends on how you want the data to be written.
The above code is the easiest way. If you want to write more info, use the same pw.print or pw.println() methods with the other info.
You could also chose to serialize the Objects and write them to the file.
for eg.
class T implements Serializable
{
....///....
your stuff
}
T t1 = new T();
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(new File("your file")));
out.writeObject(t1);
This will write the object out to the file,
0To read back the object, use
ObjectInputStream out = new ObjectInputStream(new FileInputStream(new File("your file")));
T t1 = (T) out.readObject();
Hope this helps.
Ashwin.

[Jay Brass]

Thanks Ashwin.
That was almost too easy. I guess I can stop work on that record class full of char []'s now huh?
J

[Jay Brass]

Hey Ashwin or anyone,
The above works great if I only want one record in any give file. But what if I want more than one record? If I put in account number, firstname, last name and balance, how do I put in a new record in the same file with a new account number name and balance that doesn't overwrite the one already there? Do I have to pw.println them all at once as one long string?
Maybe I should start work on that record class again.
any thoughts??
thx
J

[Ajith Kallambella]

Jay,
I am almost sure, one can write any number of objects using successive calls to writeObject().
For example,

    out.writeObject(AccountObject1);
    out.writeObject(AccountObject2);
    out.writeObject(AccountObject3);
    ...   
    ...   

Also, if you want to just append few more records to an already existing file, you can open the underlying FileOutputStream with an append flag( see the documentation for overloaded constructor of FileOutputStream ).
Though I haven't tried this( writing/reading multiple objects ) myself, it should be possible. After all, what good it is if java limits one object per serialized file!!

Hope that helps,
Ajith

[Jay Brass]

writeobject, append? hhhmmmmmm sounds logical. OK, I'll give it a whirl. I don't think I will shelve that record class just yet though.
Thanks Ajith
J