Programming Forums > Application Development > Java

cwl157 · May 14th, 2008, 10:53 AM

Now that it is summer I have some more time to work on that online battleship game. I have it where 1 client can send moves to the server and the server executes the moves on the board and sends the board back to the client and detects when all the ships have been sunk and the game is over. Now I need to figure out how to make it turn based so 2 people running the client can take turns playing the game. If someone could look at this code and tell me how to do that. I know its probably not the cleanest or the best way to do what i am doing. This is the first time i have ever done a client server thing like this before so the organization of it is probably wrong and thats probably why i cant get 2 players to take turns. When i try to run the commented out code for the second person i get a nullPointerException on the one client and a cast exception on the other client. How should i organize this where 2 people can run this client connect to a server and exchange moves with the server and play battleship against each other? I know i can't be that far off. Thanks here is the code:
Client class

 java Syntax (Toggle Plain Text) 
import java.net.*;
import java.io.*;
import java.util.*;
import ship.*;
 
public class Client
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
    static Board b;
 
    public static void main(String[] args) throws IOException
    {   
         int counter = 0;
         initializePlayer();
         boolean playerWins = false;
         while (!playerWins)
         {
           takeTurn();
           counter = (Integer) receiveObject();
           if (counter == 4)
           {
               playerWins = true;
           } // end if
        } // end while
        if (playerWins)
        {
           receive();
           b = (Board) receiveObject();
           System.out.println();
           b.printBoard();
           System.out.println();
       } // end if 
 
    } // end main
 
    // this initializes 1 player by sending its board and playerName to the Server
    static void initializePlayer()
    {
       b = new Board();
        try
        {
           connection = new Socket(InetAddress.getByName("192.168.1.102"), 1234);
           streams();
 
           // receiving to send name
           receive();
           String getName = promptUser();
           send(getName);
           send(b);
           b.printBoard();
           b = ((Board) receiveObject());
           System.out.println();
           System.out.println("Board after ships are added");
           b.printBoard();
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in initializePlayer " + e);
        } // end catch
    } // end initializePlayer
    static void takeTurn()
    {
        try
        {
           // receiving to take turn
           String receive = receive();
           String rowCol = promptUser();
           send(rowCol);
           send(b);
           receive();
           b = ((Board) receiveObject());
           System.out.println();
           System.out.println("Board after move");
           b.printBoard();
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in takeTurn" + e);
        } // end catch
    } // end takeTurn
      // establish the streams
      private static void streams() throws IOException
      {
         output=new ObjectOutputStream(connection.getOutputStream());
         output.flush();
         input=new ObjectInputStream(connection.getInputStream());
      } // end streams
 
      private static void send(Object b)
      {
         try
         {
            output.writeObject(b);
            output.flush();
         } // end try
         catch(IOException e)
         {
             System.out.println("Caught IOException in send " + e);
         } // end catch
      } // end send
 
      private static String receive() throws IOException
      {
         String test = "";
         try
            {
               test = (String) input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receiveObject
 
      private static Object receiveObject() throws IOException
      {
         Object test = new Object();
         try
            {
               test = input.readObject();
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receiveObject
 
      // take the row line from the client
     private static String getRow(String line)
      {
         String row = "";
         // take the first char in the string which is the row
         char rowC = line.charAt(0);
         // convert it to a string and return it.
         row = Character.toString(rowC);
         System.out.println(row);
         return row;
      } // end getRow
 
     // take the column line from the client
     private static String getCol(String line)
      {
         String col = "";
         // take the first char in the string which is the row
         char colC = line.charAt(2);
         // convert it to a string and return it.
         col = Character.toString(colC);
         System.out.println(col);
         return col;
      } // end getRow
 
     // get input from the user to play game or exit
  public static String promptUser() throws IOException
  {
	BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in));
	int lineToInt = 0;	
 
         String line = null;
	 try
	 {
		line = keyInput.readLine();
	 } // end try
	 //catches bad user input and throws exception
	 catch (NumberFormatException ex)
	 {
	 	System.out.print("Error bad data: ");
	 } // end catch
 
	return line;
  } // end promptUser
 
} // end Server
import java.net.*;
import java.io.*;
import java.util.*;
import ship.*;

public class Client
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
    static Board b;
    
    public static void main(String[] args) throws IOException
    {   
         int counter = 0;
         initializePlayer();
         boolean playerWins = false;
         while (!playerWins)
         {
           takeTurn();
           counter = (Integer) receiveObject();
           if (counter == 4)
           {
               playerWins = true;
           } // end if
        } // end while
        if (playerWins)
        {
           receive();
           b = (Board) receiveObject();
           System.out.println();
           b.printBoard();
           System.out.println();
       } // end if 
         
    } // end main
    
    // this initializes 1 player by sending its board and playerName to the Server
    static void initializePlayer()
    {
       b = new Board();
        try
        {
           connection = new Socket(InetAddress.getByName("192.168.1.102"), 1234);
           streams();
           
           // receiving to send name
           receive();
           String getName = promptUser();
           send(getName);
           send(b);
           b.printBoard();
           b = ((Board) receiveObject());
           System.out.println();
           System.out.println("Board after ships are added");
           b.printBoard();
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in initializePlayer " + e);
        } // end catch
    } // end initializePlayer
    static void takeTurn()
    {
        try
        {
           // receiving to take turn
           String receive = receive();
           String rowCol = promptUser();
           send(rowCol);
           send(b);
           receive();
           b = ((Board) receiveObject());
           System.out.println();
           System.out.println("Board after move");
           b.printBoard();
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in takeTurn" + e);
        } // end catch
    } // end takeTurn
      // establish the streams
      private static void streams() throws IOException
      {
         output=new ObjectOutputStream(connection.getOutputStream());
         output.flush();
         input=new ObjectInputStream(connection.getInputStream());
      } // end streams
      
      private static void send(Object b)
      {
         try
         {
            output.writeObject(b);
            output.flush();
         } // end try
         catch(IOException e)
         {
             System.out.println("Caught IOException in send " + e);
         } // end catch
      } // end send
      
      private static String receive() throws IOException
      {
         String test = "";
         try
            {
               test = (String) input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receiveObject
      
      private static Object receiveObject() throws IOException
      {
         Object test = new Object();
         try
            {
               test = input.readObject();
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receiveObject
      
      // take the row line from the client
     private static String getRow(String line)
      {
         String row = "";
         // take the first char in the string which is the row
         char rowC = line.charAt(0);
         // convert it to a string and return it.
         row = Character.toString(rowC);
         System.out.println(row);
         return row;
      } // end getRow
     
     // take the column line from the client
     private static String getCol(String line)
      {
         String col = "";
         // take the first char in the string which is the row
         char colC = line.charAt(2);
         // convert it to a string and return it.
         col = Character.toString(colC);
         System.out.println(col);
         return col;
      } // end getRow
     
     // get input from the user to play game or exit
  public static String promptUser() throws IOException
  {
	BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in));
	int lineToInt = 0;	
    
         String line = null;
	 try
	 {
		line = keyInput.readLine();
	 } // end try
	 //catches bad user input and throws exception
	 catch (NumberFormatException ex)
	 {
	 	System.out.print("Error bad data: ");
	 } // end catch
	 
	return line;
  } // end promptUser
      
} // end Server

Server class

 java Syntax (Toggle Plain Text) 
import java.io.*;
import java.net.*;
import ship.*;
 
// this is to test sending an entire board over the network
 
public class testRun
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
    static Player p1;
    static Player p2;
    static Board b1;
    static Board b2;
    static Sub subs;
    static BattleShip battleShips;
    static Patrol patrols;
    static Carrier carriers;
 
    public static void main(String[] args) throws IOException
    {
       boolean playerWins = false;
       boolean playerOneTurn = true;
 
        receivePlayer1();
 
        // this is when there is only 1 player
        while (!playerWins)
        {
           takeTurn1();
           send((Integer)p1.counter);
           if (p1.endGame(p1.counter))
           {
               playerWins = true;
           } // end if
        } // end while
        /* this is for 2 players
        while (!playerWins)
        {
          if (playerOneTurn)
          {
             takeTurn1();
             // check to see if player won the game
             if (p1.endGame(p1.counter))
             {
                 playerWins = true;
             } // end if
             playerOneTurn = false;
          } // end playerOneTurn
          else if (!playerOneTurn)
          {
              takeTurn2();
              // check to see if player won the game
              if (p2.endGame(p2.counter))
              {
                 playerWins = true;
              } // end if   
              playerOneTurn = true;
          } // end else if
        } // end while
        */
        if (playerWins)
        {
           String wonGameInfo = p1.name + " has won the game!\n" + p1.name + "'s final board";
           send(wonGameInfo);
           send(b1);
           System.out.println();
       } // end if
    } // end main
 
    static void receivePlayer1()
    {
       // initialize Player 1
       b1 = new Board();
       String namePrompt = "Please enter a Player name: ";
       String name = "";
        try
        {
          ServerSocket s = new ServerSocket(1234);
          connection = s.accept();
          streams();
          send(namePrompt);
          name = (String) receive();
          p1 = new Player(name);
          System.out.println("Player's name is " + p1.name);
          b1 = (Board)receive();
          System.out.println("The empty board is ");
          b1.printBoard();
          // set the board
          subs = new Sub();
          battleShips = new BattleShip();
          patrols = new Patrol();
          carriers = new Carrier();
          // set board
          p1.setSub(b1, subs);
          p1.setBattleShip(b1, battleShips);
          p1.setPatrol(b1, patrols);
          p1.setCarrier(b1, carriers);
          System.out.println(p1.name + "'s board: ");
          System.out.println();
          b1.printBoard();
          send((Board) b1);
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in receivePlayer " + e);
        } // end catch
    } // end receivePlayer1
 
    /*static void receivePlayer2()
    {
       // initialize Player 2
       b2 = new Board();
       String namePrompt = "Please enter a Player name: ";
       String name = "";
        try
        {
          ServerSocket s = new ServerSocket(1234);
          connection = s.accept();
          streams();
          send(namePrompt);
          name = (String) receive();
          p2 = new Player(name);
          System.out.println("Player's name is " + p2.name);
          b2 = (Board)receive();
          System.out.println("The empty board is ");
          b2.printBoard();
          // set the board
          subs = new Sub();
          battleShips = new BattleShip();
          patrols = new Patrol();
          carriers = new Carrier();
          // set board
          p2.setSub(b2, subs);
          p2.setBattleShip(b2, battleShips);
          p2.setPatrol(b2, patrols);
          p2.setCarrier(b2, carriers);
          System.out.println(p2.name + "'s board: ");
          System.out.println();
          b2.printBoard();
          send((Board) b2);
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in receivePlayer " + e);
        } // end catch
    } // end receivePlayer2
     */
 
    // get the move from the user and take turn
    static void takeTurn1() throws IOException
    {
        String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: ";
        int row = 0;
        int col = 0;
        send((String) getRowCol);
        String receivedRowCol = (String) receive();
        row = Integer.parseInt(getRow((String) receivedRowCol));
        col = Integer.parseInt(getCol((String) receivedRowCol));
        String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n";
        send((String) rowColAre);
        System.out.println("The row is " + row);
        System.out.println("The col is " + col);
        b1 = (Board) receive();
        p1.takeTurn(b1, subs, battleShips, patrols, carriers, row, col);
        b1.printBoard();
        send((Board) b1);
        //send((Board) b1);
    } // end takeTurn1
 
    // get the move from the user and take turn for player 2
   /* static void takeTurn2() throws IOException
    {
        String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: ";
        int row = 0;
        int col = 0;
        send((String) getRowCol);
        String receivedRowCol = (String) receive();
        row = Integer.parseInt(getRow((String) receivedRowCol));
        col = Integer.parseInt(getCol((String) receivedRowCol));
        String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n";
        send((String) rowColAre);
        System.out.println("The row is " + row);
        System.out.println("The col is " + col);
        b2 = (Board) receive();
        p2.takeTurn(b1, subs, battleShips, patrols, carriers, row, col);
        b2.printBoard();
        send((Board) b2);
        //send((Board) b1);
    } // end takeTurn1
    */
 
     private static void send(Object b)
     {
       try
       {
         output.writeObject(b);
         output.flush();
       } // end try
       catch(IOException ioException)
       {
       }
     } // end send
 
   // establish the streams
    private static void streams() throws IOException
    {
       output=new ObjectOutputStream(connection.getOutputStream());
       output.flush();
       input=new ObjectInputStream(connection.getInputStream());
    } // end streams
 
     private static Object receive() throws IOException
     {
        Object test = new Board();
        try
        {
           test = input.readObject();
        }  // end try
        catch(ClassNotFoundException classNotFoundException)
        {
           System.out.print("\nUnknown object recieved");
        } // end catch
         return test;
      } // end receive
 
     // take the row line from the client
     private static String getRow(String line)
      {
         String row = "";
         // take the first char in the string which is the row
         char rowC = line.charAt(0);
         // convert it to a string and return it.
         row = Character.toString(rowC);
         System.out.println(row);
         return row;
      } // end getRow
 
     // take the column line from the client
     private static String getCol(String line)
      {
         String col = "";
         // take the first char in the string which is the row
         char colC = line.charAt(2);
         // convert it to a string and return it.
         col = Character.toString(colC);
         System.out.println(col);
         return col;
      } // end getCol
 
} // end testRun
import java.io.*;
import java.net.*;
import ship.*;

// this is to test sending an entire board over the network

public class testRun
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
    static Player p1;
    static Player p2;
    static Board b1;
    static Board b2;
    static Sub subs;
    static BattleShip battleShips;
    static Patrol patrols;
    static Carrier carriers;
    
    public static void main(String[] args) throws IOException
    {
       boolean playerWins = false;
       boolean playerOneTurn = true;
     
        receivePlayer1();
        
        // this is when there is only 1 player
        while (!playerWins)
        {
           takeTurn1();
           send((Integer)p1.counter);
           if (p1.endGame(p1.counter))
           {
               playerWins = true;
           } // end if
        } // end while
        /* this is for 2 players
        while (!playerWins)
        {
          if (playerOneTurn)
          {
             takeTurn1();
             // check to see if player won the game
             if (p1.endGame(p1.counter))
             {
                 playerWins = true;
             } // end if
             playerOneTurn = false;
          } // end playerOneTurn
          else if (!playerOneTurn)
          {
              takeTurn2();
              // check to see if player won the game
              if (p2.endGame(p2.counter))
              {
                 playerWins = true;
              } // end if   
              playerOneTurn = true;
          } // end else if
        } // end while
        */
        if (playerWins)
        {
           String wonGameInfo = p1.name + " has won the game!\n" + p1.name + "'s final board";
           send(wonGameInfo);
           send(b1);
           System.out.println();
       } // end if
    } // end main
    
    static void receivePlayer1()
    {
       // initialize Player 1
       b1 = new Board();
       String namePrompt = "Please enter a Player name: ";
       String name = "";
        try
        {
          ServerSocket s = new ServerSocket(1234);
          connection = s.accept();
          streams();
          send(namePrompt);
          name = (String) receive();
          p1 = new Player(name);
          System.out.println("Player's name is " + p1.name);
          b1 = (Board)receive();
          System.out.println("The empty board is ");
          b1.printBoard();
          // set the board
          subs = new Sub();
          battleShips = new BattleShip();
          patrols = new Patrol();
          carriers = new Carrier();
          // set board
          p1.setSub(b1, subs);
          p1.setBattleShip(b1, battleShips);
          p1.setPatrol(b1, patrols);
          p1.setCarrier(b1, carriers);
          System.out.println(p1.name + "'s board: ");
          System.out.println();
          b1.printBoard();
          send((Board) b1);
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in receivePlayer " + e);
        } // end catch
    } // end receivePlayer1
    
    /*static void receivePlayer2()
    {
       // initialize Player 2
       b2 = new Board();
       String namePrompt = "Please enter a Player name: ";
       String name = "";
        try
        {
          ServerSocket s = new ServerSocket(1234);
          connection = s.accept();
          streams();
          send(namePrompt);
          name = (String) receive();
          p2 = new Player(name);
          System.out.println("Player's name is " + p2.name);
          b2 = (Board)receive();
          System.out.println("The empty board is ");
          b2.printBoard();
          // set the board
          subs = new Sub();
          battleShips = new BattleShip();
          patrols = new Patrol();
          carriers = new Carrier();
          // set board
          p2.setSub(b2, subs);
          p2.setBattleShip(b2, battleShips);
          p2.setPatrol(b2, patrols);
          p2.setCarrier(b2, carriers);
          System.out.println(p2.name + "'s board: ");
          System.out.println();
          b2.printBoard();
          send((Board) b2);
        } // end try
        catch(IOException e)
        {
            System.out.println("Caught IOException in receivePlayer " + e);
        } // end catch
    } // end receivePlayer2
     */
    
    // get the move from the user and take turn
    static void takeTurn1() throws IOException
    {
        String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: ";
        int row = 0;
        int col = 0;
        send((String) getRowCol);
        String receivedRowCol = (String) receive();
        row = Integer.parseInt(getRow((String) receivedRowCol));
        col = Integer.parseInt(getCol((String) receivedRowCol));
        String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n";
        send((String) rowColAre);
        System.out.println("The row is " + row);
        System.out.println("The col is " + col);
        b1 = (Board) receive();
        p1.takeTurn(b1, subs, battleShips, patrols, carriers, row, col);
        b1.printBoard();
        send((Board) b1);
        //send((Board) b1);
    } // end takeTurn1
    
    // get the move from the user and take turn for player 2
   /* static void takeTurn2() throws IOException
    {
        String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: ";
        int row = 0;
        int col = 0;
        send((String) getRowCol);
        String receivedRowCol = (String) receive();
        row = Integer.parseInt(getRow((String) receivedRowCol));
        col = Integer.parseInt(getCol((String) receivedRowCol));
        String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n";
        send((String) rowColAre);
        System.out.println("The row is " + row);
        System.out.println("The col is " + col);
        b2 = (Board) receive();
        p2.takeTurn(b1, subs, battleShips, patrols, carriers, row, col);
        b2.printBoard();
        send((Board) b2);
        //send((Board) b1);
    } // end takeTurn1
    */
    
     private static void send(Object b)
     {
       try
       {
         output.writeObject(b);
         output.flush();
       } // end try
       catch(IOException ioException)
       {
       }
     } // end send
    
   // establish the streams
    private static void streams() throws IOException
    {
       output=new ObjectOutputStream(connection.getOutputStream());
       output.flush();
       input=new ObjectInputStream(connection.getInputStream());
    } // end streams
 
     private static Object receive() throws IOException
     {
        Object test = new Board();
        try
        {
           test = input.readObject();
        }  // end try
        catch(ClassNotFoundException classNotFoundException)
        {
           System.out.print("\nUnknown object recieved");
        } // end catch
         return test;
      } // end receive
    
     // take the row line from the client
     private static String getRow(String line)
      {
         String row = "";
         // take the first char in the string which is the row
         char rowC = line.charAt(0);
         // convert it to a string and return it.
         row = Character.toString(rowC);
         System.out.println(row);
         return row;
      } // end getRow
     
     // take the column line from the client
     private static String getCol(String line)
      {
         String col = "";
         // take the first char in the string which is the row
         char colC = line.charAt(2);
         // convert it to a string and return it.
         col = Character.toString(colC);
         System.out.println(col);
         return col;
      } // end getCol
     
} // end testRun

Freaky Chris · May 14th, 2008, 1:18 PM

I don't have the time to read all of your code and write some of my own code at the moment im revise for exams, fun fun fun. But something like this may help you.

1) Player Connects to server
2) Server checks for free players, whilst player waits for a player
3) Server sends client details to each player, sets player1's turns to true
4) Player1 then moves and returns the board to the server
5) Server Checks for a win, else
6) Server changes player1 turn to false and sets player2 turn to true, and send the board to player2
7) and so on, until the game is won.

Sorry if this doesn't help at all.

Chris

Wizard1988 · May 14th, 2008, 3:29 PM

If you think about it the server shouldn't really be sending the board to anyone. After each player sets up their battleships the program might send the sizes and coordinates of their ships to the server. Each player will know the location of their own ships but not the enemy's (the basis of the game). Now, when a player decides to attack you could just send that coordinate to the server and have it verify if its a hit/miss or if there is a winner and send the result back to the client so it could update the display. I didn't read your code so I'm not sure how it works, but you could just have the server update a player turn status. If it is a player's turn then the client would enable a button which would submit their next move or so.

Those are just some of my thoughts.

cwl157 · May 14th, 2008, 4:45 PM

wizard, i thought about this. In fact i have a version of this where all the server does is pass the moves between clients but in order for the server to verify the move it needs to have copies of the boards. I was thinking if the clients send the board and moves and the server plays the game and sends the moves and board back to the clients then it could tell when the game is over and send that as well.

Freaky Chris,
As for what you are saying how do i make the server check for free players and then how do i make the turns go back and forth, right now it just sits with one player when the other one is connected. I thought calling receivePlayer1 and receivePlayer2 would make it alternate but it doesn't work that way and i think the server gets confused about what is sent from who when and stuff

Wizard1988 · May 14th, 2008, 5:34 PM

I'm not understanding why the client(s) would need to send the setup board to the server more than once. After the server received the two boards it should be able to figure out the results if it received the moves to be played.

cwl157 · May 14th, 2008, 9:10 PM

O now i see what your saying. Yea i tried that and then just had the server send the board back to the client after 1 move but for some reason the client was still receiving the board with no move done, so i looked at how i was doing it when setting up the ships and i was sending the board to the server, setting the ships and sending the board back so for the moves, i ended up sending the board to the server and then the server sending the board back and then it worked. So if there is a different way this can be done i would love to know how to do it.

Freaky Chris · May 15th, 2008, 11:17 AM

AS to how you would check for free players, simple use a status flag so to speak. You spawn a thread for a new 1v1 game. Set a variable to false such as, FULL = False, then when a new client joins the server check any threads running games for any False's. If one is found then join that game and set its FULL variable to true.

Chris

cwl157 · May 15th, 2008, 12:26 PM

yea i was wondering about threads for this, unfortunatly i have zero experience using threads but it would make it so more then 1 game could be going on at once right?

Freaky Chris · May 15th, 2008, 12:36 PM

indeed it would. You would have to set up a few different threads, one to handle each new player and then no doubt one for games, im not entierly sure how one would set it up atm, if i have time later i'll have a think about the logic behind it and get back to you with that. Threads are reasonable easy to understand, i recomend checking threading out it could prove very useful.
there is a different approach that one could take i suppose. The server handles all connecting clients. Then it calls a different app with connection details that automatically connects to two people to play the gae and that then acts as the server for the game and the clients are no long connected to the main server. Once the game ends the clients are reconnected to the main server.

All very dodgy im guessing im just thinking about things differently thats all

Chris

May 14th, 2008, 10:53 AM	#1
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 343 Rep Power: 4	back to online battleship Now that it is summer I have some more time to work on that online battleship game. I have it where 1 client can send moves to the server and the server executes the moves on the board and sends the board back to the client and detects when all the ships have been sunk and the game is over. Now I need to figure out how to make it turn based so 2 people running the client can take turns playing the game. If someone could look at this code and tell me how to do that. I know its probably not the cleanest or the best way to do what i am doing. This is the first time i have ever done a client server thing like this before so the organization of it is probably wrong and thats probably why i cant get 2 players to take turns. When i try to run the commented out code for the second person i get a nullPointerException on the one client and a cast exception on the other client. How should i organize this where 2 people can run this client connect to a server and exchange moves with the server and play battleship against each other? I know i can't be that far off. Thanks here is the code: Client class java Syntax (Toggle Plain Text) import java.net.; import java.io.; import java.util.; import ship.; public class Client { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; static Board b; public static void main(String[] args) throws IOException { int counter = 0; initializePlayer(); boolean playerWins = false; while (!playerWins) { takeTurn(); counter = (Integer) receiveObject(); if (counter == 4) { playerWins = true; } // end if } // end while if (playerWins) { receive(); b = (Board) receiveObject(); System.out.println(); b.printBoard(); System.out.println(); } // end if } // end main // this initializes 1 player by sending its board and playerName to the Server static void initializePlayer() { b = new Board(); try { connection = new Socket(InetAddress.getByName("192.168.1.102"), 1234); streams(); // receiving to send name receive(); String getName = promptUser(); send(getName); send(b); b.printBoard(); b = ((Board) receiveObject()); System.out.println(); System.out.println("Board after ships are added"); b.printBoard(); } // end try catch(IOException e) { System.out.println("Caught IOException in initializePlayer " + e); } // end catch } // end initializePlayer static void takeTurn() { try { // receiving to take turn String receive = receive(); String rowCol = promptUser(); send(rowCol); send(b); receive(); b = ((Board) receiveObject()); System.out.println(); System.out.println("Board after move"); b.printBoard(); } // end try catch(IOException e) { System.out.println("Caught IOException in takeTurn" + e); } // end catch } // end takeTurn // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static void send(Object b) { try { output.writeObject(b); output.flush(); } // end try catch(IOException e) { System.out.println("Caught IOException in send " + e); } // end catch } // end send private static String receive() throws IOException { String test = ""; try { test = (String) input.readObject(); System.out.print("\n" + test); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receiveObject private static Object receiveObject() throws IOException { Object test = new Object(); try { test = input.readObject(); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receiveObject // take the row line from the client private static String getRow(String line) { String row = ""; // take the first char in the string which is the row char rowC = line.charAt(0); // convert it to a string and return it. row = Character.toString(rowC); System.out.println(row); return row; } // end getRow // take the column line from the client private static String getCol(String line) { String col = ""; // take the first char in the string which is the row char colC = line.charAt(2); // convert it to a string and return it. col = Character.toString(colC); System.out.println(col); return col; } // end getRow // get input from the user to play game or exit public static String promptUser() throws IOException { BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in)); int lineToInt = 0; String line = null; try { line = keyInput.readLine(); } // end try //catches bad user input and throws exception catch (NumberFormatException ex) { System.out.print("Error bad data: "); } // end catch return line; } // end promptUser } // end Server import java.net.; import java.io.; import java.util.; import ship.; public class Client { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; static Board b; public static void main(String[] args) throws IOException { int counter = 0; initializePlayer(); boolean playerWins = false; while (!playerWins) { takeTurn(); counter = (Integer) receiveObject(); if (counter == 4) { playerWins = true; } // end if } // end while if (playerWins) { receive(); b = (Board) receiveObject(); System.out.println(); b.printBoard(); System.out.println(); } // end if } // end main // this initializes 1 player by sending its board and playerName to the Server static void initializePlayer() { b = new Board(); try { connection = new Socket(InetAddress.getByName("192.168.1.102"), 1234); streams(); // receiving to send name receive(); String getName = promptUser(); send(getName); send(b); b.printBoard(); b = ((Board) receiveObject()); System.out.println(); System.out.println("Board after ships are added"); b.printBoard(); } // end try catch(IOException e) { System.out.println("Caught IOException in initializePlayer " + e); } // end catch } // end initializePlayer static void takeTurn() { try { // receiving to take turn String receive = receive(); String rowCol = promptUser(); send(rowCol); send(b); receive(); b = ((Board) receiveObject()); System.out.println(); System.out.println("Board after move"); b.printBoard(); } // end try catch(IOException e) { System.out.println("Caught IOException in takeTurn" + e); } // end catch } // end takeTurn // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static void send(Object b) { try { output.writeObject(b); output.flush(); } // end try catch(IOException e) { System.out.println("Caught IOException in send " + e); } // end catch } // end send private static String receive() throws IOException { String test = ""; try { test = (String) input.readObject(); System.out.print("\n" + test); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receiveObject private static Object receiveObject() throws IOException { Object test = new Object(); try { test = input.readObject(); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receiveObject // take the row line from the client private static String getRow(String line) { String row = ""; // take the first char in the string which is the row char rowC = line.charAt(0); // convert it to a string and return it. row = Character.toString(rowC); System.out.println(row); return row; } // end getRow // take the column line from the client private static String getCol(String line) { String col = ""; // take the first char in the string which is the row char colC = line.charAt(2); // convert it to a string and return it. col = Character.toString(colC); System.out.println(col); return col; } // end getRow // get input from the user to play game or exit public static String promptUser() throws IOException { BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in)); int lineToInt = 0; String line = null; try { line = keyInput.readLine(); } // end try //catches bad user input and throws exception catch (NumberFormatException ex) { System.out.print("Error bad data: "); } // end catch return line; } // end promptUser } // end Server Server class java Syntax (Toggle Plain Text) import java.io.; import java.net.; import ship.; // this is to test sending an entire board over the network public class testRun { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; static Player p1; static Player p2; static Board b1; static Board b2; static Sub subs; static BattleShip battleShips; static Patrol patrols; static Carrier carriers; public static void main(String[] args) throws IOException { boolean playerWins = false; boolean playerOneTurn = true; receivePlayer1(); // this is when there is only 1 player while (!playerWins) { takeTurn1(); send((Integer)p1.counter); if (p1.endGame(p1.counter)) { playerWins = true; } // end if } // end while / this is for 2 players while (!playerWins) { if (playerOneTurn) { takeTurn1(); // check to see if player won the game if (p1.endGame(p1.counter)) { playerWins = true; } // end if playerOneTurn = false; } // end playerOneTurn else if (!playerOneTurn) { takeTurn2(); // check to see if player won the game if (p2.endGame(p2.counter)) { playerWins = true; } // end if playerOneTurn = true; } // end else if } // end while / if (playerWins) { String wonGameInfo = p1.name + " has won the game!\n" + p1.name + "'s final board"; send(wonGameInfo); send(b1); System.out.println(); } // end if } // end main static void receivePlayer1() { // initialize Player 1 b1 = new Board(); String namePrompt = "Please enter a Player name: "; String name = ""; try { ServerSocket s = new ServerSocket(1234); connection = s.accept(); streams(); send(namePrompt); name = (String) receive(); p1 = new Player(name); System.out.println("Player's name is " + p1.name); b1 = (Board)receive(); System.out.println("The empty board is "); b1.printBoard(); // set the board subs = new Sub(); battleShips = new BattleShip(); patrols = new Patrol(); carriers = new Carrier(); // set board p1.setSub(b1, subs); p1.setBattleShip(b1, battleShips); p1.setPatrol(b1, patrols); p1.setCarrier(b1, carriers); System.out.println(p1.name + "'s board: "); System.out.println(); b1.printBoard(); send((Board) b1); } // end try catch(IOException e) { System.out.println("Caught IOException in receivePlayer " + e); } // end catch } // end receivePlayer1 /static void receivePlayer2() { // initialize Player 2 b2 = new Board(); String namePrompt = "Please enter a Player name: "; String name = ""; try { ServerSocket s = new ServerSocket(1234); connection = s.accept(); streams(); send(namePrompt); name = (String) receive(); p2 = new Player(name); System.out.println("Player's name is " + p2.name); b2 = (Board)receive(); System.out.println("The empty board is "); b2.printBoard(); // set the board subs = new Sub(); battleShips = new BattleShip(); patrols = new Patrol(); carriers = new Carrier(); // set board p2.setSub(b2, subs); p2.setBattleShip(b2, battleShips); p2.setPatrol(b2, patrols); p2.setCarrier(b2, carriers); System.out.println(p2.name + "'s board: "); System.out.println(); b2.printBoard(); send((Board) b2); } // end try catch(IOException e) { System.out.println("Caught IOException in receivePlayer " + e); } // end catch } // end receivePlayer2 / // get the move from the user and take turn static void takeTurn1() throws IOException { String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: "; int row = 0; int col = 0; send((String) getRowCol); String receivedRowCol = (String) receive(); row = Integer.parseInt(getRow((String) receivedRowCol)); col = Integer.parseInt(getCol((String) receivedRowCol)); String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n"; send((String) rowColAre); System.out.println("The row is " + row); System.out.println("The col is " + col); b1 = (Board) receive(); p1.takeTurn(b1, subs, battleShips, patrols, carriers, row, col); b1.printBoard(); send((Board) b1); //send((Board) b1); } // end takeTurn1 // get the move from the user and take turn for player 2 / static void takeTurn2() throws IOException { String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: "; int row = 0; int col = 0; send((String) getRowCol); String receivedRowCol = (String) receive(); row = Integer.parseInt(getRow((String) receivedRowCol)); col = Integer.parseInt(getCol((String) receivedRowCol)); String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n"; send((String) rowColAre); System.out.println("The row is " + row); System.out.println("The col is " + col); b2 = (Board) receive(); p2.takeTurn(b1, subs, battleShips, patrols, carriers, row, col); b2.printBoard(); send((Board) b2); //send((Board) b1); } // end takeTurn1 / private static void send(Object b) { try { output.writeObject(b); output.flush(); } // end try catch(IOException ioException) { } } // end send // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static Object receive() throws IOException { Object test = new Board(); try { test = input.readObject(); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receive // take the row line from the client private static String getRow(String line) { String row = ""; // take the first char in the string which is the row char rowC = line.charAt(0); // convert it to a string and return it. row = Character.toString(rowC); System.out.println(row); return row; } // end getRow // take the column line from the client private static String getCol(String line) { String col = ""; // take the first char in the string which is the row char colC = line.charAt(2); // convert it to a string and return it. col = Character.toString(colC); System.out.println(col); return col; } // end getCol } // end testRun import java.io.; import java.net.; import ship.; // this is to test sending an entire board over the network public class testRun { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; static Player p1; static Player p2; static Board b1; static Board b2; static Sub subs; static BattleShip battleShips; static Patrol patrols; static Carrier carriers; public static void main(String[] args) throws IOException { boolean playerWins = false; boolean playerOneTurn = true; receivePlayer1(); // this is when there is only 1 player while (!playerWins) { takeTurn1(); send((Integer)p1.counter); if (p1.endGame(p1.counter)) { playerWins = true; } // end if } // end while /* this is for 2 players while (!playerWins) { if (playerOneTurn) { takeTurn1(); // check to see if player won the game if (p1.endGame(p1.counter)) { playerWins = true; } // end if playerOneTurn = false; } // end playerOneTurn else if (!playerOneTurn) { takeTurn2(); // check to see if player won the game if (p2.endGame(p2.counter)) { playerWins = true; } // end if playerOneTurn = true; } // end else if } // end while / if (playerWins) { String wonGameInfo = p1.name + " has won the game!\n" + p1.name + "'s final board"; send(wonGameInfo); send(b1); System.out.println(); } // end if } // end main static void receivePlayer1() { // initialize Player 1 b1 = new Board(); String namePrompt = "Please enter a Player name: "; String name = ""; try { ServerSocket s = new ServerSocket(1234); connection = s.accept(); streams(); send(namePrompt); name = (String) receive(); p1 = new Player(name); System.out.println("Player's name is " + p1.name); b1 = (Board)receive(); System.out.println("The empty board is "); b1.printBoard(); // set the board subs = new Sub(); battleShips = new BattleShip(); patrols = new Patrol(); carriers = new Carrier(); // set board p1.setSub(b1, subs); p1.setBattleShip(b1, battleShips); p1.setPatrol(b1, patrols); p1.setCarrier(b1, carriers); System.out.println(p1.name + "'s board: "); System.out.println(); b1.printBoard(); send((Board) b1); } // end try catch(IOException e) { System.out.println("Caught IOException in receivePlayer " + e); } // end catch } // end receivePlayer1 /static void receivePlayer2() { // initialize Player 2 b2 = new Board(); String namePrompt = "Please enter a Player name: "; String name = ""; try { ServerSocket s = new ServerSocket(1234); connection = s.accept(); streams(); send(namePrompt); name = (String) receive(); p2 = new Player(name); System.out.println("Player's name is " + p2.name); b2 = (Board)receive(); System.out.println("The empty board is "); b2.printBoard(); // set the board subs = new Sub(); battleShips = new BattleShip(); patrols = new Patrol(); carriers = new Carrier(); // set board p2.setSub(b2, subs); p2.setBattleShip(b2, battleShips); p2.setPatrol(b2, patrols); p2.setCarrier(b2, carriers); System.out.println(p2.name + "'s board: "); System.out.println(); b2.printBoard(); send((Board) b2); } // end try catch(IOException e) { System.out.println("Caught IOException in receivePlayer " + e); } // end catch } // end receivePlayer2 / // get the move from the user and take turn static void takeTurn1() throws IOException { String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: "; int row = 0; int col = 0; send((String) getRowCol); String receivedRowCol = (String) receive(); row = Integer.parseInt(getRow((String) receivedRowCol)); col = Integer.parseInt(getCol((String) receivedRowCol)); String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n"; send((String) rowColAre); System.out.println("The row is " + row); System.out.println("The col is " + col); b1 = (Board) receive(); p1.takeTurn(b1, subs, battleShips, patrols, carriers, row, col); b1.printBoard(); send((Board) b1); //send((Board) b1); } // end takeTurn1 // get the move from the user and take turn for player 2 / static void takeTurn2() throws IOException { String getRowCol = "Please enter a row and col 0-9 so it looks like this 1,2: "; int row = 0; int col = 0; send((String) getRowCol); String receivedRowCol = (String) receive(); row = Integer.parseInt(getRow((String) receivedRowCol)); col = Integer.parseInt(getCol((String) receivedRowCol)); String rowColAre = "The row is " + row + "\nThe Col is " + col + "\n"; send((String) rowColAre); System.out.println("The row is " + row); System.out.println("The col is " + col); b2 = (Board) receive(); p2.takeTurn(b1, subs, battleShips, patrols, carriers, row, col); b2.printBoard(); send((Board) b2); //send((Board) b1); } // end takeTurn1 */ private static void send(Object b) { try { output.writeObject(b); output.flush(); } // end try catch(IOException ioException) { } } // end send // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static Object receive() throws IOException { Object test = new Board(); try { test = input.readObject(); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receive // take the row line from the client private static String getRow(String line) { String row = ""; // take the first char in the string which is the row char rowC = line.charAt(0); // convert it to a string and return it. row = Character.toString(rowC); System.out.println(row); return row; } // end getRow // take the column line from the client private static String getCol(String line) { String col = ""; // take the first char in the string which is the row char colC = line.charAt(2); // convert it to a string and return it. col = Character.toString(colC); System.out.println(col); return col; } // end getCol } // end testRun

May 14th, 2008, 1:18 PM	#2
Freaky Chris Professional Programmer Join Date: Dec 2007 Location: England Posts: 269 Rep Power: 1	Re: back to online battleship I don't have the time to read all of your code and write some of my own code at the moment im revise for exams, fun fun fun. But something like this may help you. 1) Player Connects to server 2) Server checks for free players, whilst player waits for a player 3) Server sends client details to each player, sets player1's turns to true 4) Player1 then moves and returns the board to the server 5) Server Checks for a win, else 6) Server changes player1 turn to false and sets player2 turn to true, and send the board to player2 7) and so on, until the game is won. Sorry if this doesn't help at all. Chris __________________ Steven Skiena - Algorithms

May 14th, 2008, 3:29 PM	#3
Wizard1988 Professional Programmer Join Date: Oct 2005 Location: Chitown Posts: 417 Rep Power: 4	Re: back to online battleship If you think about it the server shouldn't really be sending the board to anyone. After each player sets up their battleships the program might send the sizes and coordinates of their ships to the server. Each player will know the location of their own ships but not the enemy's (the basis of the game). Now, when a player decides to attack you could just send that coordinate to the server and have it verify if its a hit/miss or if there is a winner and send the result back to the client so it could update the display. I didn't read your code so I'm not sure how it works, but you could just have the server update a player turn status. If it is a player's turn then the client would enable a button which would submit their next move or so. Those are just some of my thoughts. __________________ JG-Webdesign

May 14th, 2008, 4:45 PM	#4
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 343 Rep Power: 4	Re: back to online battleship wizard, i thought about this. In fact i have a version of this where all the server does is pass the moves between clients but in order for the server to verify the move it needs to have copies of the boards. I was thinking if the clients send the board and moves and the server plays the game and sends the moves and board back to the clients then it could tell when the game is over and send that as well. Freaky Chris, As for what you are saying how do i make the server check for free players and then how do i make the turns go back and forth, right now it just sits with one player when the other one is connected. I thought calling receivePlayer1 and receivePlayer2 would make it alternate but it doesn't work that way and i think the server gets confused about what is sent from who when and stuff Last edited by cwl157; May 14th, 2008 at 4:55 PM.

May 14th, 2008, 5:34 PM	#5
Wizard1988 Professional Programmer Join Date: Oct 2005 Location: Chitown Posts: 417 Rep Power: 4	Re: back to online battleship I'm not understanding why the client(s) would need to send the setup board to the server more than once. After the server received the two boards it should be able to figure out the results if it received the moves to be played. __________________ JG-Webdesign

May 14th, 2008, 9:10 PM	#6
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 343 Rep Power: 4	Re: back to online battleship O now i see what your saying. Yea i tried that and then just had the server send the board back to the client after 1 move but for some reason the client was still receiving the board with no move done, so i looked at how i was doing it when setting up the ships and i was sending the board to the server, setting the ships and sending the board back so for the moves, i ended up sending the board to the server and then the server sending the board back and then it worked. So if there is a different way this can be done i would love to know how to do it.

May 15th, 2008, 11:17 AM	#7
Freaky Chris Professional Programmer Join Date: Dec 2007 Location: England Posts: 269 Rep Power: 1	Re: back to online battleship AS to how you would check for free players, simple use a status flag so to speak. You spawn a thread for a new 1v1 game. Set a variable to false such as, FULL = False, then when a new client joins the server check any threads running games for any False's. If one is found then join that game and set its FULL variable to true. Chris __________________ Steven Skiena - Algorithms

May 15th, 2008, 12:26 PM	#8
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 343 Rep Power: 4	Re: back to online battleship yea i was wondering about threads for this, unfortunatly i have zero experience using threads but it would make it so more then 1 game could be going on at once right?

May 15th, 2008, 12:36 PM	#9
Freaky Chris Professional Programmer Join Date: Dec 2007 Location: England Posts: 269 Rep Power: 1	Re: back to online battleship indeed it would. You would have to set up a few different threads, one to handle each new player and then no doubt one for games, im not entierly sure how one would set it up atm, if i have time later i'll have a think about the logic behind it and get back to you with that. Threads are reasonable easy to understand, i recomend checking threading out it could prove very useful. there is a different approach that one could take i suppose. The server handles all connecting clients. Then it calls a different app with connection details that automatically connects to two people to play the gae and that then acts as the server for the game and the clients are no long connected to the main server. Once the game ends the clients are reconnected to the main server. All very dodgy im guessing im just thinking about things differently thats all Chris __________________ Steven Skiena - Algorithms

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