Help with 2 easy functions?

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

public class Program2
{
  
public static void Playgame() throws IOException
{
 try
 {
  String YesorNo;
  BufferedReader keyboard;
  boolean loopNeeded;
  
  keyboard = new BufferedReader(new InputStreamReader(System.in));
  
  System.out.println ("Would you like to play the GCF game?\n Please type Yes or No and press Enter");
  YesorNo = keyboard.readLine();																			// assigns the entered string to the variable YesorNo
  
  
  if (YesorNo.equalsIgnoreCase("yes"))
  gcfNumbers();																								//sends the program to gcfNumbers
  else if (YesorNo.equalsIgnoreCase("no"))
  {
   System.out.println("Thanks for playing the GCF game!");
   System.exit(1);
  }
  else 
  {
   System.out.println("Please type Yes or No and press Enter");
   Playgame();
  }
 }
 catch   (NullPointerException e)
 {
  System.out.println("Oh Inferior One, why must you try to spoil my programs?");
  Playgame();
 }
}
public static void twoNumGCF()
{

}
public static void threeNumGCF()
{
	
}
public static void gcfNumbers()
{
 try 
  {
   Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();

   
   if (a == 2)
   {
     twoNumGCF();
    }
   else if (a == 3)
    {
     threeNumGCF();
    }
    else 
    {
     System.out.println("Please type 2 or 3 numbers, please try again! "); 
     gcfNumbers();
    }
  }
  
  catch (NullPointerException e)
  {
   System.out.println("Why must you bother me so, Hanosh?\n");
   }
 
};
}