Reading Files - Beginning Java - page 502

The available() method for a BufferedInputStream returns an estimate of the number of bytes you
can read or skip over without blocking as a value of type int . A stream can be blocked if another thread of
execution is reading from the same file.

Marking a Stream
You can mark the current position in a buffered stream by calling mark() for the stream object. The ar-
gument to this method is an integer specifying the number of bytes that can be read or skipped before the
current mark is invalidated. You can return to the position in the stream that you have marked by calling the
reset() method for the stream object. This enables you to read a section of a file repeatedly.
The markSupported() method for a BufferedInputStream object tests if the stream supports marking
the stream. It returns true if mark() and reset() are supported and false otherwise.
Let's try an example.

TRY IT OUT: Reading a Binary File
In this example, you read the fibonacci.bin file that you created in the Junk directory in the previous
chapter.

import java.nio.file.*;
import java.nio.*;
import java.io.*;

public class StreamInputFromFile {
public static void main(String[] args) {

Path file = Paths.get(System.getProperty("user.home")).
resolve("Beginning Java
Stuff").resolve("fibonnaci.bin");

if(!Files.exists(file)) {
System.out.println(file + " does not exist. Terminating
program.");
System.exit(1);

}

final int count = 6; // Number of values

to be read each time

// Buffer to hold count values
ByteBuffer buf = ByteBuffer.allocate(8*count);

LongBuffer values = buf.asLongBuffer();
byte[] bytes = buf.array(); // Backing array for

buf

int totalRead = 0; // Total value read