为什么循环不会停止迭代？

Question

我是一名 Java 初学者，正在为我的班级编写一个 gui tic-tac-toe 程序。 （没有玩家，只有电脑生成）。

我的程序中的一切都按预期工作，除了一件事；似乎我对checkWinner 的方法调用的放置位置不正确，因为 X 和 O 的分配总是完成。为什么一有赢家就不会结束循环？

它将根据方法调用返回正确的获胜者，但 for 循环将继续迭代并填充其余部分（因此有时看起来 x 和 o 都赢了，或者一个赢了两次）。我一直在发疯，认为这可能是我的 checkWinner 方法调用和 if 语句的位置。当我设置winner = true; 时不应该取消循环吗？我试过把它放在每个 for 循环的内部和外部，但没有运气:(

我已经在代码右侧标记了我认为是问题的区域//这里有什么问题？//。感谢您的任何意见！ :)

  public void actionPerformed(ActionEvent e)
  {
    int total = 0, i = 0;
    boolean winner = false;


    //stop current game if a winner is found
    do{

      // Generate random # 0-1 for the labels and assign 
      // X for a 0 value and O for a 1 value

      for (int row = 0; row < gameboard.length; row++) //rows
      {
        for (int col = 0; col < gameboard[row].length; col++) //columns
        { 

          //Generate random number
          gameboard[row][col] = (int)(Math.random() * 2);  

          //Assign proper values
          if(gameboard[row][col] == 0)
          {
            labels[i].setText("X");
            gameboard[row][col] = 10; //this will help check for the winner
          }

          else if(gameboard[row][col] == 1)
          {
            labels[i].setText("O");   
            gameboard[row][col] = 100; //this will help check for winner
          }             


          /**Send the array a the method to find a winner
            The x's are counted as 10s
            The 0s are counted as 100s
            if any row, column or diag = 30, X wins
            if any row, column or diag = 300, Y wins
            else it will be a tie
            */

          total = checkWinner(gameboard);      **//Is this okay here??//**
          if(total == 30 || total == 300)        //
            winner = true;                //Shouldn't this cancel the do-while?


          i++; //next label

        }
      }//end for
    }while(!winner);//end while



    //DISPLAY WINNER
    if(total == 30)
      JOptionPane.showMessageDialog(null, "X is the Winner!");
    else if(total == 300)
      JOptionPane.showMessageDialog(null, "0 is the Winner!");
    else
      JOptionPane.showMessageDialog(null, "It was a tie!");
  }

Answer 1

最简单的方法是一次中断所有循环。 （即使有些人不喜欢这样）

outerwhile: while(true){

  // Generate random # 0-1 for the labels and assign 
  // X for a 0 value and O for a 1 value

  for (int row = 0; row < gameboard.length; row++) //rows
  {
    for (int col = 0; col < gameboard[row].length; col++) //columns
    { 

      total = checkWinner(gameboard);     
      if(total == 30 || total == 300)        
        break outerwhile;  //leave outer while, implicit canceling all inner fors.


      i++; //next label
    }
  }//end for
}//end while

但是，这将不允许“平局”选项，因为如果没有找到获胜者，则基本上会重新开始游戏。要让平局，你根本不需要外边，当找到赢家时，可以同时离开两个边：

  Boolean winner = false;
  outerfor: for (int row = 0; row < gameboard.length; row++) //rows
  {
    for (int col = 0; col < gameboard[row].length; col++) //columns
    { 

      total = checkWinner(gameboard);     
      if(total == 30 || total == 300){        
        winner = true;     
        break outerfor;  //leave outer for, implicit canceling inner for.

      }

      i++; //next label
    }
  }//end for

  if (winner){
    //winner
  }else{
     //tie.
  }

Answer 2

首先，您的代码遍历一个板并生成 X 和 O 的随机标记。这会导致一些非常奇怪的板状态，总是逐行填充，并且 X 和 O 标记的数量可能不平衡.

恕我直言，您应该以相反的方式组织代码以填充类似于真正游戏的棋盘。我的意思是一系列 9 标记“XOXOXOXOX”分布在黑板上。

设Labels labels 是一个九字符数组，初始化为 9 个空格。

public int doGame( Labels labels)
{
    labels = "         ";
    int itisXmove = true;              // player X or O turn
    for( int movesLeft = 9; movesLeft > 0; movesLeft --)
    {
        int position =          // 0 .. movesLeft-1
                (int) Math.floor(Math.random() * movesLeft);

        for( int pos = 0; pos < 9; pos ++)        // find position
            if( labels[ pos] == " ")              // unused pos?
                if( position-- == 0)              // countdown
                {
                    if( itisXmove)                // use the pos
                        labels[ pos] = "X";       // for current player
                    else
                        labels[ pos] = "O";
                    break;
                }

        int result = checkWinner( labels);        // who wins (non-zero)?
        if( result != 0)
            return result;

        itisXmove = ! itisXmove;                  // next turn
    }
    return 0;                                     // a tie
}

然后

public void actionPerformed(ActionEvent e)
{
    Labels labels;

    int result = doGame( labels);

    if( result == valueForX)
        JOptionPane.showMessageDialog(null, "X is the Winner!");
    else if( result == valueForO)
        JOptionPane.showMessageDialog(null, "O is the Winner!");
    else
        JOptionPane.showMessageDialog(null, "It's a tie!");

    for( int rowpos = 0; rowpos < 9; rowpos += 3)
    {
        for( int colpos = 0; colpos < 3; colpos ++)
            /* output (char)label[ rowpos + colpos] */;

        /* output (char)newline */;
    }
}

Answer 3

我认为您应该更改循环条件并再添加一个布尔值。

您有一个“平局”条件，但目前您只检查获胜者。没有 checkWinner 代码的唯一解释是您每次都遇到平局。

所以...

boolean tie;
boolean winner;

do {
//your stuff
}
while(!(tie || winner))

编辑：我没有意识到您将 while 循环放在 for 循环之外，您需要跳出 for 循环才能检查 while 条件。

//stop current game if a winner is found
    do{

      for (int row = 0; row < gameboard.length; row++) //rows
      {
        for (int col = 0; col < gameboard[row].length; col++) //columns
        { 
            if(winner || tie)
                break;
        }//end for

        if(winner || tie)
            break;
      }//end for
    }while(!(winner || tie));//end while
//the rest of your stuff here

Answer 4

在两个 for 循环完成之前，您不会检查 winner 的值。在设置winner = true 后立即添加break，并添加一个

if (winner)
{
    break;
}

到您的外部 for 循环的开头或结尾。

Answer 5

您的问题是您的 do/while 语句围绕 for 语句。因此，for 语句最终会在到达while 语句之前运行整个周期。解决此问题的解决方案是检查 for 语句中的获胜者并打破：

//stop current game if a winner is found
do {

    for (int row = 0; row < gameboard.length; row++) //rows
    {
        for (int col = 0; col < gameboard[row].length; col++) //columns
        { 

            // ... your other code ...

            total = checkWinner(gameboard);
            if(total == 30 || total == 300) {
                winner = true;
                break; // end current for-loop
            }

            i++; //next label
        }

        if (winner) break; // we have a winner so we want to kill the for-loop
    } //end for

} while(!winner); //end while

因此，您应该能够遍历两个 for 语句并在获胜者处中断。您的代码似乎也没有处理绑定案例，但我猜您已经知道了。