// ---------------------------------
// Sample program demonstrating how to read two Strings per
// line from a file. The Strings should be separated by a tab
// and will be echoed out in reverse order.
//
// Fritz Ruehr, Willamette University Computer Science
// CS 241, Spring 1999
// 
// ------
//
// To test this program out, compile it, then issue a command
// such as:
//
// 	java StringsEcho echotest.txt
// 
// (i.e., it takes the filename as its 1st command-line argument)
// 
// ---------------------------------

// This import statement gives us access to the "io" library

import java.io.* ;
import java.util.* ;


// We always need at least one class declaration to hold the main method

class StringsEcho{

	// ------------
	// We always need a void main method, too; this one
	// has to throw IOException since it reads a file

	public static void main(String[] args) throws IOException {

		// ------------
		// Here we open the file given on the command line
		// and then read lines, breaking at tabs with tabber.
		// For non-empty files, we loop until the input is
		// exhausted, echoing strings as we go

		FileReader f = new FileReader(args[0]) ;

		if (f!=null){

		  BufferedReader infile = new BufferedReader(f) ;

		  while (infile.ready()) {

		    StringTokenizer tabber =
			new StringTokenizer(infile.readLine(), "\t") ;

		    String first = tabber.nextToken() ;
		    String second = tabber.nextToken() ;

		    System.out.println(second + "\t" + first) ;
		  }
		}
	
		// ------------
		// When input is exhausted, we should close the file.

		System.out.println("\n... and then end of file") ;
	
		f.close() ;

	} // main method

} // StringsEcho class