writing to binary files

Hi,

I'm currently using ObjectOutputStream.writeInt() to write to binary files.

It works if the user types an integer. But obviously fails if the user types in a character string.

Is there a way to write to a binary file without having to check each character to see if it's a string or int, double, etc?

Thanks

Quote:

---

Originally Posted by TopNFalvors

I'm currently using ObjectOutputStream.writeInt() to write to binary files.
It works if the user types an integer. But obviously fails if the user types in a character string.

---

Obviously? This makes no sense.

Quote:

---

Is there a way to write to a binary file without having to check each character to see if it's a string or int, double, etc?

---

You don't have to check any of that. If you are writing an ObjectOutputStream though, you need to make sure that you write out objects that implement a Serializable interface. Otherwise your question is very short on necessary details. Please see my link below on how to ask smart questions to see what details I'm talking about that will make your question in fact answerable.

Your're right, that makes no sense.

I'm writing data into the binary file like this:

Code:

---

Scanner myScanner = new Scanner(System.in);
int intTapeKey = 0;

System.out.println("Provide tape key:");
intTapeKey = myScanner.nextInt();

---

Is there a better way to enter in binary data? Because if the user enters in a character, it will obviously fail(due to the nextInt statement).

Thanks!

Ok, I solved the writing binary problem I was having.

Here's what I'm doing now that seems to be working:

Code:

---

myStream = new ObjectOutputStream(new FileOutputStream(myFile));
Scanner myScanner = new Scanner(System.in);
String tapeKey = "";

System.out.println("Provide tape key:");
tapeKey = myScanner.nextLine();

myStream.writeObject(tapeKey);

---

Thanks

I'm lost here.
What do you mean by a binary file?
Why are you using an ObjectOutputStream for anything other than outputting an Object (ie serilising an object to somewhere)?

Well I'm writing to a file called key.bin that stores data in binary format to be read by a key-reading program.

Thanks

And does that key-reading program use an ObjectInputStream?

It's just that that stream strikes me as plain wrong for what it appears you're doing.

Well I'm trying to read and write to a binary file...not a normal, human-readble text file.

I figured ObjectInputStream and ObjectOutputStream would be best.

Should I use something else?

Thanks

FileOutputStream.
write(). Well one of the write() methods anyway.

You only want the bytes, but the ObjectOutputStream will print lots of stuff to do with the object you're writing.

The following:

Code:

---

    public static void main(String[] args) {
        try {
            ObjectOutputStream oos = new ObjectOutputStream(System.out);
            int i = 10;
            oos.writeObject(10);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

---

produces:

Code:

---

(garbage)sr(garbage)java.lang.Integer(garbage)

---

etc etc. Which the ObjectInputStream would use to recreate an Integer object of value 10.

Now, I doubt that's what you want.

I tried one version that wrote/read bytes, but when reading back, it didn't read back in plain english...it was the human-unreadble binary.

Yes.
That's what a binary file is.

If you want to write to a bin then you have to expect it to be a bin when read back.