import java.io.*;

import java.util.*;

public class VeryLongDriver
{
	protected BufferedReader fileReader;

	protected PrintWriter fileWriter;

	public PrintWriter openFiles()
	{
	        final String IN_FILE_PROMPT =
        	      	"\n\nPlease enter the path for the input file: ";

        	final String OUT_FILE_PROMPT =
              		"\n\nPlease enter the path for the output file: ";

        	BufferedReader keyboardReader = new BufferedReader
                                        (new InputStreamReader (System.in));

        	String inFilePath,
                       outFilePath;

        	boolean pathsOK = false;

        	while (!pathsOK)
        	{
            		try
            		{
                		System.out.print (IN_FILE_PROMPT);
                		inFilePath = keyboardReader.readLine();
                		fileReader = new BufferedReader (new FileReader (inFilePath));
                		System.out.print (OUT_FILE_PROMPT);
                		outFilePath = keyboardReader.readLine();
                		fileWriter = new PrintWriter (new FileWriter (outFilePath));
                		pathsOK = true;	     
            		} // try
            		catch (IOException e)
            		{
                		System.out.println (e);
            		} // catch I/O exception
        	} // while 
        	return fileWriter;
    	} // method openFiles


	public void testVeryLongIntMethods()
    	{
	        final String LINE_MESSAGE = "The line is\n";

        	final String STRING_CONSTRUCTOR = "VeryLongInt";

        	final String TO_STRING = "toString";

        	final String ADD = "add";

        	final String VERY_LONG_MESSAGE = "Here is the VeryLongInt: ";

        	final String BAD_METHOD =
                    "The line entered does not represent a legal method.";

        	StringTokenizer tokens;

        	String line,
               	       method,
                       argument;

        	VeryLongInt veryLong = null,
                            otherVeryLong;

        	while (true)
        	{
           		try
           		{
               			line = fileReader.readLine();
               			if (line == null)
                   			break;
               			fileWriter.println (LINE_MESSAGE + line);
               			tokens = new StringTokenizer (line);
               			method = tokens.nextToken();
               			if (method.equals (STRING_CONSTRUCTOR))
               			{
                   			if (tokens.hasMoreTokens())
                   			{
                       				argument = tokens.nextToken();
                       				veryLong = new VeryLongInt (argument);
                   			} // if more tokens
                   			else
						veryLong = new VeryLongInt (null);
               			} // string-parameter constructor
               			else if (method.equals (TO_STRING))
               			{
               			} // toString method
               			else if (method.equals (ADD))
               			{
                   			if (tokens.hasMoreTokens())
                   			{
                       				argument = tokens.nextToken();
                       				otherVeryLong = new VeryLongInt (argument);
                       				veryLong.add (otherVeryLong);
                   			} // if more tokens
                   			else
                       				veryLong = new VeryLongInt (null);
               			} // add method
               			else
                   			fileWriter.println (BAD_METHOD);
               			fileWriter.println (VERY_LONG_MESSAGE + veryLong + "\n\n");
            		} // try
            		catch (IOException e)
            		{
                		fileWriter.println (e + "\n\n");
            		} // catch IOException
            		catch (NullPointerException e)
            		{
                 		fileWriter.println (e + "\n\n");
            		} // catch NoSuchElementException
         	} // while
    } // method testVeryLongIntMethods

} // class VeryLongDriver