What I have accomplished so far...

Design and implement a Nim class and a NimGame application to allow two human players to play the game of Nim. The game starts with four piles of stones. The first pile has 3 stones, the second pile has 5 stones, the third pile has 7 stones, and the last pile has 9 stones. The players take turns removing stones. On a single turn a player may only take stones from a single pile.
The loser of the game is the player to take the very last stone.


This is what I need help on, I entered this for the time being.. but it's obviously not the right way to do it.

A player may not take more than half the pile, except when it’s the last stone in the pile.

while ( stones >= 4 )
            {
               //Display error message, and ask user to re enter number.
               System.out.print("Invalid number, You can't take more than half the pile");
               stones = input.nextInt();
            }

Below is all the code I have.

package nimgame;

import java.util.Scanner;

public class NimGame
{
    public static int player = 1;
    public static int [] _board;

    public static void main(String[] args)
    {

        //Declare variables
        int pile = 0; //Which file to pick from
        int stones = 0; //How many stones to pick
        int counter = 0; //If the game is over or not



        //Scanner 
        Scanner input = new Scanner(System.in);

        NimClass myAssistant = new NimClass();
        myAssistant.displayBoard(); //Set board up

        //Begin loop
        while(counter == 0)
        {
        //Choose pile you want to remove stones from.
        System.out.print("Player " + player + " Please enter the pile you wish" +
                         " to remove from. (1, 2, 3 or 4)\n");
        //Get a pile number
        pile = input.nextInt();

          //Only allow user to enter a valid pile number.
          while (pile < 1 || pile > 4)
            {
               //Display error message, and ask user to re enter number.
               System.out.print("Invalid number, Please enter a pile # 1-4 ");
               pile = input.nextInt();
            }

        //Enter # of stones you want to remove.
        System.out.print("Player " + player + " Please enter the amount of" +
                          " stones you wish to remove\n");
        stones = input.nextInt();
        myAssistant.playerMove(pile, stones);

         //Only allow user to take half the pile.
          while ( stones >= 4 )
            {
               //Display error message, and ask user to re enter number.
               System.out.print("Invalid number, You can't take more than half the pile");
               stones = input.nextInt();
            }

            //Determine what player is entering the values.
            if (player == 1)
                player = 2;
            else
                player = 1;

             //Display board / determine the winner of the game.
             myAssistant.displayBoard();
             myAssistant.determineWinner();


            if (myAssistant.determineWinner() != -1)
                counter = 1;

        }


    }
}
package nimgame;

public class NimClass
{
    //Board for the game array
    public static int [] _board;

    
    public NimClass()
    {
   
        //Determing # of stones in each pile at the beginning.
        _board = new int [4];
        _board[0] = 3; //Pile 1  3 stones
        _board[1] = 5; //Pile 2  5 stones
        _board[2] = 7; //Pile 3  7 stones
        _board[3] = 9; //Pile 4  9 stones

        System.out.println("Welcome to the Game of Nim\n" +
                           "You'll need to first pick a pile\n" +
                           "Then select how many stones you wish to remove\n");
    }


   //Display the game board
    public void displayBoard()
    {
        for(int row = 0; row < 4; row++)
        {
            if(_board[row] == 0)
                System.out.print("    0    ");
            else
                System.out.print("     " + _board[row] + "   ");
        }
            //Print out the piles
            System.out.println("\n  Pile 1   Pile 2   Pile 3   Pile 4\n");

    }

    //Determine the player's moves
    public boolean playerMove (int pile, int stones)
    {
      if ((pile < 1) || (pile > _board.length))
      {
          return false;
      }

        if (_board[pile - 1] >= stones)
        {
          _board[pile - 1] -= stones;
          return true;
        }
     else
        {
          return false;
        }
    }


    //Determine the winner of the game
    public int determineWinner()
    {
        boolean complete = true;
        int winner = -1;

        //Checking the piles to see if they're empty.
        if((_board[0] == 0) && ( _board[1]== 0) && ( _board[2]==0) && ( _board[3]==0))

            winner = NimGame.player; //Determine winner
            complete = false;

        if(complete == false && winner == 1)
        {
            //Display the results of player 1 winning.
            System.out.println("Player 1 Wins!");
            winner = 0;
        }

        if(complete == false && winner == 2)
        {
            //Display the results of player 2 winning.
            System.out.println("Player 2 Wins!");
            winner = 0;
        }
        return winner;

    }
}

Any help would be appreciated!

Do you have an algorithm or design for how you want you program to work?
Once you get that, we can help you when you having problems writing the program.

This is my understanding of what you want: If the player tries to remove more than or half of how many ever stones there are left in a pile, it will show an error unless it is the last stone.

You will need to first calculate how many stones the 'half' is. So the following should be the pseudocode:

while ( stones is >= (the number of stones left in the pile) divided by 2)
{
if (the number of stones in the pile == 1)//which is the last stone left
break;//break out of the while loop and continue
else
//show error message
}

I haven't tested it but it sounds logically correct. Hope that helped.

You could add as

while (stones is >= (the number of stones left in the pile divided by 2) and the number of stones left in the pile is > 0)

This case, you should not need the break in the loop.

Some people do not mark thread as solved once they get what they want. I would not expect anything about that... :P

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