Re: java -nio- reading a file- whats wrong with this

From:

"Daniel Pitts" <googlegroupie@coloraura.com>

Newsgroups:

comp.lang.java.programmer

Date:

2 Feb 2007 12:59:25 -0800

Message-ID:

<1170449965.472465.8370@v33g2000cwv.googlegroups.com>

On Feb 2, 12:32 pm, "Craig" <craigsb...@gmail.com> wrote:

                java.io.FileInputStream zipStream = new java.io.FileInputStream
(path);
                File file=new File(path);
                System.out.println(file.length());
                FileChannel fc= zipStream.getChannel();
                ByteBuffer buffer=ByteBuffer.allocate((int)file.length());
                buffer.clear();
                System.out.println(buffer.capacity());
                fc.read(buffer);
                fc.close();
                zipStream.close();
                byte[] b=new byte[buffer.capacity()];
                System.out.println(b.length);
                buffer.get(b,0,b.length);
                return b;

I am getting a BufferUnderflowException when I do buffer.get(b);
I don't know why this is wrong because all the three print statements
gives the same value: 9932

The second question I have is,how can I avoid int casting when I do
bytebuffer.allocate. I am concerned about handling larger files.

Kindly Reply.
Thanks,
Craig

I'm reminded of Bradley Video's little message on there video
cassettes. "Be kind, please rewind"
<sscce>
import java.io.File;
import java.io.FileInputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class TestNIO {
    public static void main(String...args) throws Exception {
        final File file = new File("test.dat");
        final FileInputStream input = new FileInputStream(file);
        final FileChannel channel = input.getChannel();
        final ByteBuffer byteBuffer = ByteBuffer.allocate((int)
file.length());
        channel.read(byteBuffer);
        channel.close();
        input.close();
        final byte[] bytes = new byte[byteBuffer.capacity()];
        byteBuffer.rewind();
        byteBuffer.get(bytes);
    }
}
</sscce>