import java.nio.* ;

public class WriteBuffer {

    public static void main(String [] args) {

        int BUF_SIZE = 1024 ; 
        ByteBuffer buffer = ByteBuffer.allocateDirect(BUF_SIZE) ;

        byte [] src = "hello world".getBytes() ;
        buffer.put(src) ;              // Write data to buffer

        buffer.flip() ;                // Prepare buffer for draining

        byte [] dst = new byte [2048] ;
        buffer.get(dst, 0, buffer.limit()) ;  // Read data from buffer

        System.out.println(new String(dst, 0, buffer.limit())) ;

        buffer.clear() ;               // Empty buffer (optional here).
    }
}