I wrote some binary data in a file using the FileOutputStream class. Now I want to read it with the Scanner class, but it can't. Is it possible to read a binary file with Scanner class? If yes, then how?
Edit:
I solve it by in.nextline();
-
Check this : stackoverflow.com/questions/5347327/…Saurabh Gokhale– Saurabh Gokhale2011-06-12 09:13:38 +00:00Commented Jun 12, 2011 at 9:13
-
2You can't read a binary file with in.readLine(). If you can read a file with Scanner its not a binary file.Peter Lawrey– Peter Lawrey2011-06-12 09:31:34 +00:00Commented Jun 12, 2011 at 9:31
-
You have more than ten questions you haven't accepted. ;)Peter Lawrey– Peter Lawrey2011-06-12 09:45:51 +00:00Commented Jun 12, 2011 at 9:45
Add a comment
|
3 Answers
To read a binary file you can use DataInputStream or ByteBuffer with NIO.
2 Comments
Mahdi_Nine
i want to use from scanner class
Peter Lawrey
@mehdi, Can you explain why using a Scanner is a requirement? You could use Scanner with a lot of work. You would still need to use DataInputStream to convert the data to text for the Scanner to consume. This would be pointless unless you have an existing library which only accepts a Scanner.
Now I want to read it with the Scanner class, but it can't.
That is a correct observation. A Scanner will not read binary data, it is not designed for that purpose. Scanners expect to be provided with an object that implements the Readable interface, whose contract specifies that only characters may be returned. It can accept an InputStream, but as the API states: Bytes from the stream are converted into characters using the underlying platform's default charset.
Is it possible to read a binary file with Scanner class? If yes, then how?
Going by the previous explanation, it is not possible, not unless you've written them in a manner so that the above process of converting bytes returns characters. If you need access to binary data from a stream, you'll need to avoid using Readers and Readable objects. You'll need to work on raw InputStreams or FilterInputStreams, that will return byte arrays or suitable objects. In your specific case, you'll need a FileInputStream.
Tips:
- Use Reader and Writer objects when working with characters in Java.
- Avoid using the above for binary data. Use InputStreams and OutputStreams instead.
- Understand how the decorator pattern is implemented in java.io.
Comments
Did you read the API docs ?
A simple text scanner which can parse primitive types and strings using regular expressions.
http://download.oracle.com/javase/1,5.0/docs/api/java/util/Scanner.html
This may help you:
3 Comments
Mahdi_Nine
i saw it but didn't see any thing that could help me!
Vineet Reynolds
@mehdi, did it not occur to you that binary data is not exactly the same as primitive types and strings? To emphasize the portion of the extract posted by Peter: A simple text scanner which can parse primitive types and strings using regular expressions.
Vineet Reynolds
@mehdi, Then why are you insisting on using a Scanner?