为什么我的等待线程即使被通知也不醒来？

Question

我有一个客户端服务器tic-tac-toe游戏，它试图为每个玩家运行不同的线程（在不同的终端），这是我在eclipse中构建的。

我的目标是让每个玩家进行移动，.notify（）另一个玩家，然后.wait（）让另一个玩家进行移动，并且交替执行该过程直到完成游戏。

toSync是用于同步

public static final Object toSync = new Object() 

物体，它是在播放器类（其由两个XPlayer和OPLAYER延长）找到。

这似乎引起该问题的行被注释掉在XPlayer和OPLAYER：

两个Xplayer和OPLAYER有主要的方法，让他们可以同时运行。 X做出第一步然后使用一个套接字将这一举动传达给服务器。
服务器将此移动传递给O，然后O将自己的移动传递回服务器。直到游戏结束，这个轮换。

由于x播放器工作正常，所以首先要做的是，一旦初始移动完成，o应该显示电路板，然后提示用户进行移动。然而，这并没有发生：x做出了动作，并且o据推测被通知，但实际上从未醒来。结束在OPlayer中评论的while循环的大括号永远不会到达（我知道通过我迄今为止所做的调试是真实的）。

类XPlayer：

import java.io.*; 

public class XPlayer 
extends Player 
implements Runnable 
{ 
    public static volatile boolean xTurn = true; 

    public XPlayer() throws IOException 
    { 
     super(); 
     mark = LETTER_X; 
    } 

    public void run() 
    { 
     try 
     { 
      System.out.println("Okay " + name + ", You will be the X-Player"); 

      synchronized(toSync) 
      { 
       Cell move = makeMove(); 
       out.println(move.toString()); 
       board.addMark 
        (move.row(),move.col(),move.mark()); 
       board.display(); 

       xTurn = false; 
       toSync.notifyAll(); //THIS IS THE LINE THAT ISNT WORKING!! 

       System.out.println(WAITING); 
      } 
      synchronized(toSync) 
      { 
       while (!xTurn) 
        {toSync.wait();} 
      } 

      while (!board.isOver()) 
      { 
       synchronized(toSync) 
       { 
        String line; 
        do {line = in.readLine();} 
        while (line == null); 

        Cell opponentMove = Cell.split(line); 
        board.addMark 
         (opponentMove.row(),opponentMove.col(), opponentMove.mark()); 

        String move = makeMove().toString(); 
        out.println(move); 
        xTurn = false; 
        toSync.notifyAll(); 

        while (!xTurn) 
         {toSync.wait();} 
       } 
      } 

      endGame(); 

      sock.close(); 
      in.close(); 
      stdin.close(); 
      out.close(); 

     } catch (InterruptedException ie) 
     { 
      System.out.println("IE IN XPLAYER! " + ie.getMessage()); 
      System.exit(1); 

     } catch (IOException ioe) 
     { 
      System.out.println("IOE IN XPLAYER! " + ioe.getMessage()); 
      System.exit(1); 
     } 
    } 
    public static void main(String[] args) 
    { 
     try 
     { 
      XPlayer x = new XPlayer(); 
      Thread t = new Thread(x); 
      t.start(); 

     } catch(IOException ioe) 
     { 
      System.err.println 
       ("IOE IN XPLAYER MAIN " + ioe.getMessage()); 
      System.exit(1); 
     } 
    } 

类OPLAYER：

import java.io.*; 

public class OPlayer 
extends Player 
implements Runnable 
{ 

    public OPlayer() throws IOException 
    { 
     super(); 
     mark = LETTER_O; 
    } 

    public void run() 
    { 
     try 
     {  
      synchronized(toSync) 
      { 
       System.out.println("Okay " + name + ", You will be the O-Player"); 

       System.out.println(WAITING); 
       while(!XPlayer.xTurn) 
        {toSync.wait();} // THIS IS THE LINE THAT ISN'T WAKING UP 

       while (!board.isOver()) 
       { 
        String line; 

        do {line = in.readLine();} 
        while (line == null); 

        Cell opponentMove = Cell.split(line); 
        board.addMark 
         (opponentMove.row(),opponentMove.col(),opponentMove.mark()); 

        Cell move = makeMove(); 
        out.println(move.toString()); 
        board.addMark(move.row(),move.col(),move.mark()); 
        board.display(); 
        XPlayer.xTurn = true; 
        toSync.notifyAll(); 

        System.out.println(WAITING); 
        while (XPlayer.xTurn) 
         {toSync.wait();}  
       } 
      } 

      endGame(); 

      sock.close(); 
      in.close(); 
      stdin.close(); 
      out.close(); 

     } catch (InterruptedException ie) 
     { 
      System.out.println("IE IN OPLAYER " + ie.getMessage()); 
      System.exit(1); 

     } catch (IOException ioe) 
     { 
      System.err.println("IOE IN OPLAYER " + ioe.getMessage()); 
      System.exit(1); 
     } 
    } 

    public static void main(String[] args) 
    { 
     try 
     { 
      OPlayer o = new OPlayer(); 
      Thread t = new Thread(o); 
      t.start(); 

     } catch(IOException ioe) 
     { 
      System.err.println("IOE IN OPLAYER MAIN" + ioe.getMessage()); 
      System.exit(1); 
     } 
    } 
} 

作为由代码指示的，在XPlayer的toSync.notifyAll（）调用不唤醒OPLAYER线程，我一旦XPlayer发起了第一步，就会陷入僵局。我相信只有那两个类才能解决问题，但为了以防万一，以下是这些类的玩家公猪队d和TTTServer： 级的球员：

import java.net.*; 
import java.io.*; 

public class Player 
implements Constants 
{ 
    protected static final Object toSync = new Object(); 

    protected Socket sock; 
    protected BufferedReader stdin; 
    protected BufferedReader in; 
    protected PrintWriter out; 

    protected String name; 
    protected char mark; 
    protected Board board; 

    public Player() throws IOException 
    { 
     sock = new Socket("localhost",1298); 
     stdin = new BufferedReader(new InputStreamReader(System.in)); 
     in = new BufferedReader(new 
       InputStreamReader(sock.getInputStream())); 
     out = new PrintWriter(sock.getOutputStream(),true); 

     System.out.println(WELCOME); 
     System.out.println("Please Enter your name:"); 
     name = stdin.readLine(); 
     board = new Board(); 
    } 

    public Cell makeMove() throws IOException 
    { 
     board.display(); 

     int row = -1; 
     int col = -1; 
     do 
     { 
      while (row < 0 || row > 2) 
      { 
       System.out.println 
        (name + ", what row would you like your next move to be in?"); 
       row = Integer.parseInt(stdin.readLine()); 
       if (row < 0 || row > 2) 
        {System.out.println("Invalid entry! Try again...");} 
      } 
      while (col < 0 || col > 2) 
      { 
       System.out.println 
        (name + ", what column would you like your next move to be in?"); 
       col = Integer.parseInt(stdin.readLine()); 
       if (col < 0 || col > 2) 
        {System.out.println("Invalid entry! Try again...");} 
      } 

      if (board.getMark(row, col) != SPACE_CHAR) 
       {System.out.println("That spot is already taken Try again...");} 

     } while (board.getMark(row,col) != SPACE_CHAR); 

     return new Cell(row,col,mark); 
    } 

    public void endGame() 
    { 
     if (board.xWins() == 1)  {System.out.println(END + XWIN);} 
     if (board.oWins() == 1)  {System.out.println(END + OWIN);} 
     else   {System.out.println(END + " It was a tie!!");} 
    } 
} 

类TTTServer：

import java.net.*; 
import java.io.*; 

public class TTTServer 
implements Constants 
{ 
    public static void main(String[] args) 
    { 
     try 
     { 
      ServerSocket ss = new ServerSocket(1298,2); 
      System.out.println("The Server is running..."); 
      Socket sock; 

      Board board = new Board(); 

      sock = ss.accept(); 
      sock = ss.accept(); 

      BufferedReader in = new BufferedReader(new 
        InputStreamReader(sock.getInputStream())); 
      PrintWriter out = new PrintWriter(sock.getOutputStream(),true); 

      do 
      { 
       String moveString; 

       do {moveString = in.readLine();} 
       while (moveString == null); 

       Cell move = Cell.split(moveString); 
       board.addMark(move.row(), move.col(), move.mark()); 

       out.println(moveString); 

      } while(!board.isOver()); 

      in.close(); 
      out.close(); 
      ss.close(); 
      sock.close(); 

     } catch(IOException ioe) 
     { 
      System.out.println("IOE IN TTTSERVER " + ioe.getMessage()); 
      System.exit(1); 
     } 

    } 
} 

类局：

public class Board 
implements Constants 
{ 
    /** 
    * A 2D char array stores the game board and 
    * the total number of marks 
    */ 
    private char theBoard[][]; 
    private int markCount; 
    /** 
    * Default constructor initializes the array and fills it with 
    * SPACE_CHARs from the Constants interface 
    */ 
    public Board() 
    { 
     markCount = 0; 
     theBoard = new char[3][]; 
     for (int i = 0; i < 3; i++) { 
      theBoard[i] = new char[3]; 
      for (int j = 0; j < 3; j++) 
       theBoard[i][j] = SPACE_CHAR; 
     } 
    } 
    /** 
    * Getter for the mark at the location specified by the arguments 
    * 
    * @param row 
    * @param column 
    * 
    * @return mark 
    */ 
    public char getMark(int row, int col) 
     {return theBoard[row][col];} 
    /** 
    * Getter for the number of moves which have been made thus far 
    * 
    * @return markCount 
    */ 
    public int getMarkCount()  {return markCount;} 
    /** 
    * @return true if the game is over, otherwise false 
    */ 
    public boolean isOver() 
    { 
     if (xWins() == 1 || oWins() == 1 || isFull()) 
      {return true;} 

     return false; 
    } 
    /** 
    * @return true if the board has been completely filled with 
    * X_CHARs and O_CHARs from Constants interface, else false 
    */ 
    public boolean isFull() 
     {return markCount == 9;} 
    /** 
    * Runs checkWinner on LETTER_X from Constants interface 
    * 
    * @return true if X has won, else false 
    */ 
    public int xWins() 
     {return checkWinner(LETTER_X);} 
    /** 
    * Runs checkWinner on LETTER_O from Constants interface 
    * 
    * @return true if O has won, else false 
    */ 
    public int oWins() 
     {return checkWinner(LETTER_O);} 
    /** 
    * Uses the formatting helper methods to display the board 
    * in the console 
    */ 
    public void display() 
    { 
     displayColumnHeaders(); 
     addHyphens(); 
     for (int row = 0; row < 3; row++) { 
      addSpaces(); 
      System.out.print(" row " + row + ' '); 
      for (int col = 0; col < 3; col++) 
       System.out.print("| " + getMark(row, col) + " "); 
      System.out.println("|"); 
      addSpaces(); 
      addHyphens(); 
     } 
    } 
    /** 
    * Add the mark in the last argument to the location specified by the 
    * first two arguments 
    * 
    * @param row 
    * @param column 
    * @param mark 
    */ 
    public void addMark(int row, int col, char mark) 
    { 
     theBoard[row][col] = mark; 
     markCount++; 
    } 
    /** 
    * Clears the board by replacing all marks with 
    * SPACE_CHARs from the Constants interface 
    */ 
    public void clear() 
    { 
     for (int i = 0; i < 3; i++) 
      for (int j = 0; j < 3; j++) 
       theBoard[i][j] = SPACE_CHAR; 
     markCount = 0; 
    } 
    /** 
    * Checks if the player with the argument mark has won the game 
    * 
    * @param mark 
    * 
    * @return true if the game was won, else false 
    */ 
    int checkWinner(char mark) { 
     int row, col; 
     int result = 0; 

     for (row = 0; result == 0 && row < 3; row++) { 
      int row_result = 1; 
      for (col = 0; row_result == 1 && col < 3; col++) 
       if (theBoard[row][col] != mark) 
        row_result = 0; 
      if (row_result != 0) 
       result = 1; 
     } 


     for (col = 0; result == 0 && col < 3; col++) { 
      int col_result = 1; 
      for (row = 0; col_result != 0 && row < 3; row++) 
       if (theBoard[row][col] != mark) 
        col_result = 0; 
      if (col_result != 0) 
       result = 1; 
     } 

     if (result == 0) { 
      int diag1Result = 1; 
      for (row = 0; diag1Result != 0 && row < 3; row++) 
       if (theBoard[row][row] != mark) 
        diag1Result = 0; 
      if (diag1Result != 0) 
       result = 1; 
     } 
     if (result == 0) { 
      int diag2Result = 1; 
      for (row = 0; diag2Result != 0 && row < 3; row++) 
       if (theBoard[row][3 - 1 - row] != mark) 
        diag2Result = 0; 
      if (diag2Result != 0) 
       result = 1; 
     } 
     return result; 
    } 

    /** 
    * The final three helper methods are called by display 
    * to format the board properly in the console 
    */ 
    void displayColumnHeaders() { 
     System.out.print("   "); 
     for (int j = 0; j < 3; j++) 
      System.out.print("|col " + j); 
     System.out.println(); 
    } 

    void addHyphens() { 
     System.out.print("   "); 
     for (int j = 0; j < 3; j++) 
      System.out.print("+-----"); 
     System.out.println("+"); 
    } 

    void addSpaces() { 
     System.out.print("   "); 
     for (int j = 0; j < 3; j++) 
      System.out.print("|  "); 
     System.out.println("|"); 
    } 
} 

Answer 1

这是你的错误：

两个Xplayer和OPLAYER有主要方法，以便他们可以同时运行。

如果你正在运行的两个main()方法，他们现在还没有遇到“同时”;他们完全是分开的过程。这意味着没有共享线程，变量，对象，通知等。如果你想分享的状态，你需要从一个单一的main()方法开始的一切：

class StarterClass { 
    public static void main(String[] args) 
    { 
     // start XPlayer thread 
     try 
     { 
      XPlayer x = new XPlayer(); 
      Thread t = new Thread(x); 
      t.start(); 

     } catch(IOException ioe) 
     { 
      System.err.println 
       ("IOE IN XPLAYER MAIN " + ioe.getMessage()); 
      System.exit(1); 
     } 

     // start OPlayer thread 
     try 
     { 
      OPlayer o = new OPlayer(); 
      Thread t = new Thread(o); 
      t.start(); 

     } catch(IOException ioe) 
     { 
      System.err.println("IOE IN OPLAYER MAIN" + ioe.getMessage()); 
      System.exit(1); 
     } 
    } 
} 

如果您的目的是让每个Player运行作为一个独立的客户端，同时交替轮流，线程同步是在错误的工具工作。您需要在您的服务器和客户端之间实现自定义消息传递，以使其保持同步。