// a simple GCDdemonstration
// John Sklar, CED 512 - fall, 2k   
   import java.applet.Applet;
   import java.awt.*;
   import java.awt.event.*;
   public class gcd extends Applet implements ActionListener
   {
      TextField integer1,integer2;
      Button action = new Button (" Find the GCD ");
      Label answer, Banner;
   

      public void init()
      {
         Font bigFont = new Font("TimesRoman", Font.ITALIC, 24);
         Font biggerFont = new Font("TimesRoman", Font.ITALIC, 30);
         Font monoFont = new Font("Courier", Font.BOLD, 24);
      

         integer1 = new TextField(5);
         integer2 = new TextField(5);
      

         Banner = new Label ("Enter two integers");
         answer = new Label("                                                             ");
      

         action.setFont(monoFont);
         answer.setFont(biggerFont);
         Banner.setFont(bigFont);
         integer1.setFont(monoFont);
         integer2.setFont(monoFont);
      

         add (Banner);
         add (integer1);
         add (integer2);
         add (action);
         add (answer);
         action.addActionListener(this);         
         integer1.addActionListener(this);
         integer2.addActionListener(this);
         setBackground(Color.white);
      }
      public void actionPerformed (ActionEvent e)
      {
         String results = new String(""); 
         int one,two,hold;       
      

         if (action.getLabel()==" Find the GCD ")
         {
            one=Integer.parseInt(integer1.getText()); 
            two=Integer.parseInt(integer2.getText());        
            if(one < 0 || two < 0)
               results = "Please... Positive integers only.";
            else{
               results = "The GCD of " + one + " and " + two + " is ";
               if(one > two){
                  hold = one;
                  one = two;
                  two = hold;
               }
               if(one != two)	
                  while(two !=0){
                     hold = one % two;
                     one = two;
                     two = hold;
                  }
               results += one; // add the number itself to the string
            }
            answer.setText (results); 
            action.setLabel(" Clear ");
            integer1.setEnabled(false);// no typing now
            integer2.setEnabled(false);// no typing now
         }
         else{ 
            Banner.setText ("Enter two integers");
            integer1.setText("");
            integer2.setText("");
            answer.setText ("              ");
            action.setLabel(" Find the GCD ");
            integer1.setEnabled(true);// ok, you can type
            integer2.setEnabled(true);// ok, you can type
         }
      }
   

   }