ReverseFile

/**
 * Use RandomAccessFile to reverse a file.
 * 
 * To use this program, specify the name of the file.
 * For example, to reverse a file called test.txt use the
 * following command line:
 * 
 *     java ReverseFile test.txt
 * 
 */

package FileIO;

import java.io.*;

/**
 * @author Administrator
 *
 */
public class ReverseFile {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// First make sure the a file has been specified.
		if  (1 != args.length) {
			System.out.println("Usage: ReverseFile name");
			return ;
		}
		
		RandomAccessFile raf;
		
		try {
			// Open the file.
			raf = new RandomAccessFile(args[0], "rw");
		} catch (FileNotFoundException exc) {
			System.out.println("Cannot Open File");
			return ;
		}
		
		try {
			int x;
			int y;
			
			// Reverse the file.
			for (long i = 0, j = raf.length() - 1; i < j; ++i, --j) {
				// Read the next set of bytes
				raf.seek(i);
				x = raf.read();
				raf.seek(j);
				y = raf.read();
				
				// Swap the bytes
				raf.seek(j);
				raf.write(x);
				raf.seek(i);
				raf.write(y);
			} 
		} catch (IOException exc) {
			System.out.println("Error Writing File");
		}
		
		try {
			raf.close();
		} catch (IOException exc) {
			System.out.println("Error Closing File");
		}
	}
}