Question

I have the following code:

        String inputFile = 'somefile.txt';         FileInputStream in = new FileInputStream(inputFile);         FileChannel ch = in.getChannel();         ByteBuffer buf = ByteBuffer.allocateDirect(BUFSIZE);  // BUFSIZE = 256          /* read the file into a buffer, 256 bytes at a time */         int rd;         while ( (rd = ch.read( buf )) != -1 ) {             buf.rewind();             for ( int i = 0; i < rd/2; i++ ) {                 /* print each character */                 System.out.print(buf.getChar());             }             buf.clear();         } 

But the characters get displayed at ?’s. Does this have something to do with Java using Unicode characters? How do I correct this?

Answer 1

You have to know what the encoding of the file is, and then decode the ByteBuffer into a CharBuffer using that encoding. Assuming the file is ASCII:

import java.util.*; import java.io.*; import java.nio.*; import java.nio.channels.*; import java.nio.charset.*;  public class Buffer {     public static void main(String args[]) throws Exception     {         String inputFile = 'somefile';         FileInputStream in = new FileInputStream(inputFile);         FileChannel ch = in.getChannel();         ByteBuffer buf = ByteBuffer.allocateDirect(BUFSIZE);  // BUFSIZE = 256          Charset cs = Charset.forName('ASCII'); // Or whatever encoding you want          /* read the file into a buffer, 256 bytes at a time */         int rd;         while ( (rd = ch.read( buf )) != -1 ) {             buf.rewind();             CharBuffer chbuf = cs.decode(buf);             for ( int i = 0; i < chbuf.length(); i++ ) {                 /* print each character */                 System.out.print(chbuf.get());             }             buf.clear();         }     } }