FileInputStream read from offset

[HowTo]

Hello,
I just ran into a probelm when reading a binary file.
The binary file contains a bunch of data which are to be assigned to
different buffers.
Now, there are occassions where a single byte of the file needs to be
twice, as it contains part of information for buffer A and another
part of information for buffer B - I know its stupid, but I didn't
design the file layout, I only have to somehow parse it....
Anyway, I use the FileInputStream class for reading the binary file
and that normally works fine. However the read (byte[], offset,
length) routine, does not really seems to position at the given
offset ... at least it does not seem to make any diffrence if I insert
(offset -1), (offset) or (offset+1).

Now, did anyone already experience a similar problem? And if you did,
how did you solve it?
Many thanks in advance

 

[Daniel Pitts]

Hello,
I just ran into a probelm when reading a binary file.
The binary file contains a bunch of data which are to be assigned to
different buffers.
Now, there are occassions where a single byte of the file needs to be
twice, as it contains part of information for buffer A and another
part of information for buffer B - I know its stupid, but I didn't
design the file layout, I only have to somehow parse it....
Anyway, I use the FileInputStream class for reading the binary file
and that normally works fine. However the read (byte[], offset,
length) routine, does not really seems to position at the given
offset ... at least it does not seem to make any diffrence if I insert
(offset -1), (offset) or (offset+1).

Now, did anyone already experience a similar problem? And if you did,
how did you solve it?
Many thanks in advance

Read the javadoc for mark()

 

[Daniele Futtorovic]

Hello,
I just ran into a probelm when reading a binary file.
The binary file contains a bunch of data which are to be assigned to
different buffers.
Now, there are occassions where a single byte of the file needs to be
twice, as it contains part of information for buffer A and another
part of information for buffer B - I know its stupid, but I didn't
design the file layout, I only have to somehow parse it....
Anyway, I use the FileInputStream class for reading the binary file
and that normally works fine. However the read (byte[], offset,
length) routine, does not really seems to position at the given
offset ... at least it does not seem to make any diffrence if I insert
(offset -1), (offset) or (offset+1).

Now, did anyone already experience a similar problem? And if you did,
how did you solve it?
Many thanks in advance

Read the javadoc for mark()

java.io.PushbackInputStream seems a tad more simple in this case.
<http://java.sun.com/javase/6/docs/api/java/io/PushbackInputStream.html>

 

[Arne Vajhøj]

I just ran into a probelm when reading a binary file.
The binary file contains a bunch of data which are to be assigned to
different buffers.
Now, there are occassions where a single byte of the file needs to be
twice, as it contains part of information for buffer A and another
part of information for buffer B - I know its stupid, but I didn't
design the file layout, I only have to somehow parse it....
Anyway, I use the FileInputStream class for reading the binary file
and that normally works fine. However the read (byte[], offset,
length) routine, does not really seems to position at the given
offset ... at least it does not seem to make any diffrence if I insert
(offset -1), (offset) or (offset+1).

Now, did anyone already experience a similar problem? And if you did,
how did you solve it?

If you need full flexibility then go for java.io.RandomAccessFile
it has a seek method.

Arne