Program doesn't recognise keyboard input. PLease help.

Question

Hi guys,
I managed with help from some of you to build my Dice Game.
It works the way it should be however I still have a small issue.
It should be working in a way that when user in the beginning puts 'r' the dice roll is performed. At the moment no matter what I put and the press Enter the dice roll is performed.
The same is for Roll and Hold. After each dice throw a human can either roll (press 'r') or hold (press 'h').
If I press 'h' then it works fine- computer turn begins, but when I just press enter it rolls again.
why is that?
Below is the code, thanks in advance for any help!
import java.util.Scanner; 
public class Assignment 
     Boolean humanTurn = true; 
     Boolean computerTurn = true; 
     int dice; 
     int humanTurnPoints, computerTurnPoints; 
     int humanTotalPoints = 0;
     int computerTotalPoints = 0;     
     public void roll() 
         dice = (int)(Math.random()*6) + 1;                  
     public int humanTurnScore() 
                 humanTurnPoints = dice + humanTurnPoints; 
                 System.out.println("You threw: " + dice);
                 System.out.println("You have scored: " + humanTurnPoints + " in your turn."); 
             } return humanTurnPoints; 
     public void humanTurnZero()
          humanTurnPoints = 0;
     public int computerTurnScore() 
                 computerTurnPoints = dice + computerTurnPoints; 
                 System.out.println("Computer has scored: " + computerTurnPoints + " in its turn."); 
             } return computerTurnPoints; 
      public void computerTurnZero()
               computerTurnPoints = 0;
     public Assignment() 
         humanGame(); 
         if(!humanTurn) 
             computerTurn(); 
     public int humanGame()
         System.out.println("To start the game please press 'r'."); 
         Scanner key = new Scanner(System.in); 
         String start = key.nextLine(); 
         if(!start.equalsIgnoreCase("R"))
                   System.out.println("To begin please press 'r'.");
         if(start.equalsIgnoreCase("R"))
                         System.out.println("You pressed 'r'."); 
                         System.out.println("Lets start.");          
         do{ 
                 roll();     
                 if(dice == 1) 
                     System.out.println("You got 1 and you lost your turn.");
                     System.out.println("Computer's GRAND TOTAL score is: " + computerTotalPoints);
                     humanTurnZero();           
                     computerTurn(); 
                 else if(dice != 1)
                     humanTotalPoints += dice;      
                          if(humanTotalPoints >= 100)   
                                 System.out.println("You threw: " + dice);
                                 System.out.println("Your GRAND TOTAL score is: " + humanTotalPoints);
                                   System.out.println("Congratulations, you win!"); 
                                   System.exit(0); 
                     humanTurnScore();     
                     System.out.println("Your GRAND TOTAL score is: " + humanTotalPoints); 
                     System.out.println("Computer's GRAND TOTAL score is: " + computerTotalPoints);
                     System.out.println("You can hold or roll again."); 
                     System.out.println("To roll again press 'r' or 'h' to hold."); 
                     Scanner keyboard = new Scanner(System.in); 
                     String choice = keyboard.nextLine(); 
                     if(choice.equalsIgnoreCase("r")) 
                         System.out.println("You pressed 'r'."); 
                         System.out.println("Lets roll again.");  
                         roll();          
                     if(choice.equalsIgnoreCase("h")) 
                         System.out.println("You pressed 'h' and loose your turn.");
                         System.out.println("Your Grand total is: " + humanTotalPoints);
                         humanTurnZero(); 
                         computerTurn(); 
            }while(humanTurn);    
         return dice; 
public int computerTurn() 
     System.out.println("Now it's computer turn."); 
     do { 
         roll(); 
         if(dice != 1) 
               computerTotalPoints += dice;
                    if(computerTotalPoints >=100) 
                           System.out.println("Computer threw: " + dice);
                           System.out.println("Computer's GRAND TOTAL score is: " + computerTotalPoints);
                             System.out.println("Game Over! the computer wins"); 
                             System.exit(0); 
             System.out.println("Computer threw: " + dice);
             System.out.println("Computer's GRAND TOTAL score is: " + computerTotalPoints);
             System.out.println("Your Grand total is: " + humanTotalPoints);
             computerTurnScore(); 
             roll(); 
         if(dice == 1)  
             System.out.println("Computer thrown 1 therefore it's your turn now."); 
             computerTurnZero(); 
             humanGame(); 
         if(computerTurnPoints >= 20) 
             System.out.println("Computer scored already " + computerTurnPoints + " you'd better start to focus."); 
             System.out.println("Please play again"); 
             humanGame(); 
     }while (computerTurn); 
     return dice; 
public static void main(String[] args) 
     new Assignment(); 
} 

Answer 1

Hi,
Thanks for that but I don't really understand that concept roll().
I did what you were saying, but now when the program just started and i press something else instead of 'r' the program terminates.
When I press correctly 'r' in the beginning and after that is human turn i pressanything else except 'r' or 'h' program continues to behave like I pressed 'r'.
public int humanGame()
         System.out.println("To start the game please press 'r'."); 
         Scanner key = new Scanner(System.in); 
         String start = key.nextLine(); 
         if(!start.equalsIgnoreCase("R"))
                   System.out.println("To begin please press 'r'.");
         if(start.equalsIgnoreCase("R"))
                         System.out.println("You pressed 'r'."); 
                         System.out.println("Lets start.");          
         do{ 
                 roll();     
                 if(dice == 1) 
                     System.out.println("You got 1 and you lost your turn.");
                     System.out.println("Computer's GRAND TOTAL score is: " + computerTotalPoints);
                     humanTurnZero();           
                     computerTurn(); 
                 else if(dice != 1)
                     humanTotalPoints += dice;      
                          if(humanTotalPoints >= 100)   
                                 System.out.println("You threw: " + dice);
                                 System.out.println("Your GRAND TOTAL score is: " + humanTotalPoints);
                                   System.out.println("Congratulations, you win!"); 
                                   System.exit(0); 
                     humanTurnScore();     
                     System.out.println("Your GRAND TOTAL score is: " + humanTotalPoints); 
                     System.out.println("Computer's GRAND TOTAL score is: " + computerTotalPoints);
                     System.out.println("You can hold or roll again."); 
                     System.out.println("To roll again press 'r' or 'h' to hold."); 
                     Scanner keyboard = new Scanner(System.in); 
                     String choice = keyboard.nextLine(); 
                     if(choice.equalsIgnoreCase("r")) 
                         System.out.println("You pressed 'r'."); 
                         System.out.println("Lets roll again.");  
                         roll();          
                     if(choice.equalsIgnoreCase("h")) 
                         System.out.println("You pressed 'h' and loose your turn.");
                         System.out.println("Your Grand total is: " + humanTotalPoints);
                         humanTurnZero(); 
                         computerTurn(); 
            }while(humanTurn);    
         return dice; 
              }return dice;
     }