import NumberItem;
import DivisorCalc;
import java.util.StringTokenizer;
import java.io.*;
 
public class GcdDriver {
	
 
  public static void main(String args[]) {
  	
		final int MAX = 4;
		NumberItem[] items = new NumberItem[MAX];
		StringTokenizer tokenizer;
		String line,file = "numbers.txt";
		int num1, num2, answer;
		int count = 0;
 
		
	try{
		
		FileReader fr = new FileReader (file);
		BufferedReader inFile = new BufferedReader (fr);
		
		line = inFile.readLine();
		while (line != null){
		
		tokenizer = new StringTokenizer (line);
	  		
		try
		 {
		 num1 = Integer.parseInt (tokenizer.nextToken());		
		 num2 = Integer.parseInt (tokenizer.nextToken());
		 items[count++] = new NumberItem (num1, num2);
		 		 
		 }
		 
		 catch (NumberFormatException exception)
		 {
		 	System.out.println ("Error in input. Line ignored:");
		    System.out.println (line);		
		 }
		
		line = inFile.readLine();
	     }
	    
	    inFile.close();	
	    
	    for (int scan = 0; scan < count; scan++)
	    System.out.println (items[scan]);	    	   
	     }
		
    catch (IOException exception)
       {
    	System.out.println (exception);
       }
    
        DivisorCalc.Gcd ();
    
}
} // class GcdDriver
 
 
import java.io.*;
 
public class DivisorCalc {
	
	private static int dividend1, dividend2, num1, num2, number1, number2;
	private static int max, answer, result;
	
	
	public void NumberItem (int number1, int number2) {
		
		num1 = number1;
		num2 = number2;
		
    }
	
	public static int Gcd (int num1, int num2) {
		
	      if(num1 > num2) // to figure larger of the two numbers
             max = num1;
           else          
             max = num2;
           
        
      while (dividend1 != dividend2) {
        
        for ( int i = 1; i < max; i++)
        
           dividend1 = num1 - max;
           dividend2 = num2 - max;
           
           max--;
     
                 
          if (dividend1 == dividend2)  
          
          answer = dividend1;
          
          System.out.println ("Greatest common divisor: " + answer);
       }             
          return answer;
 
                   
	   	     
} //class Gcd
          
} // class DivisorCalc	
 
public class NumberItem {
	
	private int num1, num2;
 
 
public  NumberItem (int number1, int number2) {
		
		num1 = number1;
		num2 = number2;
		
    }
   
}	
 
Text file is:
 
45 15
 
100 35
 
4 7
 
I love Lucy

// Computes the Greatest Common Divisor of two numbers
public long gcd ( long a, long b ) {
	
		// Make sure two numbers are positive integers
		if ( a < 0 || b < 0 ) {
			throw new RuntimeException ( "Two numbers, to compute GCD, must be positive" ) ;
		}
		
		if ( b == 0 ) {
			return a;
		}
		else {
			return gcd ( b, a % b);
		}
		
	}