Question

我正在研究udemy。我正在编写XOX游戏的代码。我想我们所有人都知道XOX游戏。我的代码正常工作，但是我不明白该代码的作用？

for (int [] winningPosition : winningPositions){
                    if (gameState[winningPosition[0]] == gameState[winningPosition[1]] && gameState[winningPosition[1]] == gameState[winningPosition[2]] &&
                            gameState[winningPosition[0]] != 2)}

我没有得到的代码在上面。请帮助我理解这一点。

{ package com.example.anild.xox;

    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.GridLayout;
    import android.widget.ImageView;
    import android.widget.LinearLayout;
    import android.widget.TextView;

    public class MainActivity extends AppCompatActivity {
        // 0 = yellow, 1 = red

        int activePlayer = 0;

        boolean gameIsActive = true;

        //2 means unplayed
        int [] gameState = {2,2,2,2,2,2,2,2,2};

        int [][] winningPositions = {{0,1,2},{3,4,5},{6,7,8},{0,3,6},{1,4,7},{2,5,8},{0,4,8},{2,4,6}};

        public void dropIn(View view) {

            ImageView counter = (ImageView) view;

            int tappedCounter = Integer.parseInt(counter.getTag().toString());

            if(gameState[tappedCounter] == 2 && gameIsActive) {

                //burada tappedCounterdaki sayıyı çekiyor yani tag'i daha sonra gamstate[] dizisine atıyor. Ve zaten hepsi 2 if koşulu sağlanıyor
                //Bir asağısında bu kural değişiyor. Bu alınan tag gametate'te artık 0 olarak saklanıyor :)

                gameState[tappedCounter] = activePlayer;

                counter.setTranslationY(-1000f);


                if (activePlayer == 0) {
                    counter.setImageResource(R.drawable.yellow);
                    activePlayer = 1;
                } else {
                    counter.setImageResource(R.drawable.red);
                    activePlayer = 0;
                }

                counter.animate().translationYBy(1000f).rotation(360).setDuration(300);

                for (int [] winningPosition : winningPositions){
                    if (gameState[winningPosition[0]] == gameState[winningPosition[1]] && gameState[winningPosition[1]] == gameState[winningPosition[2]] &&
                            gameState[winningPosition[0]] != 2){

                        //someone has won

                        gameIsActive = false;
                        String winner = "Red";
                        if(gameState[winningPosition[0]] == 0){
                            winner = "Yellow";

                        }

                        TextView winnerMessage = (TextView) findViewById(R.id.winnerMessage);

                        winnerMessage.setText(winner + "has won !");

                        LinearLayout layout = (LinearLayout)findViewById(R.id.playAgainLayout);


                        layout.setVisibility(View.VISIBLE);
                    }
                    else {
                        boolean gameIsOver = true;
                        for(int counterState : gameState) {
                            if (counterState == 2) {
                                gameIsOver = false;

                            }

                            if (gameIsOver) {
                                TextView winnerMessage = (TextView) findViewById(R.id.winnerMessage);

                                winnerMessage.setText("it's a draw");

                                LinearLayout layout = (LinearLayout)findViewById(R.id.playAgainLayout);


                                layout.setVisibility(View.VISIBLE);

                            }
                        }
                    }
                }
            }



        }

        public void playAgain(View view) {

            gameIsActive = true;

            LinearLayout layout = (LinearLayout)findViewById(R.id.playAgainLayout);
            layout.setVisibility(View.INVISIBLE);

            // 0 = yellow, 1 = red

            activePlayer = 0;



            for(int i = 0; i < gameState.length; i++) {

                gameState[i] = 2;
            }

            GridLayout gridLayout = (GridLayout) findViewById(R.id.gridLayout);

            for(int i = 0; i < gridLayout.getChildCount(); i++) {

                ((ImageView) gridLayout.getChildAt(i)).setImageResource(0);

            }
        }



        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);




        }
    }

 }

Answer 1

根据我的评论下方提出的问题进行回答：

从根本上讲，for循环的格式为

for('one object' : 'group of objects')

现在，在通常情况下，您将按照以下方式使用某些东西：

for(String oneString : arrayOfStrings)

根据您的问题，似乎您不知道可以通过将值放在大括号中来静态指定值数组。例如：

String[] arrayOfStrings = {"zero", "one", "two"};

产生的结果与以下内容完全相同：

String[] arrayOfStrings = new String[3];
arrayOfStrings[0] = "zero";
arrayOfStrings[1] = "one";
arrayOfStrings[2] = "two";

您可以使用for(String string : arrayOfStrings) ...

回到原始代码-它们在括号内嵌入了括号，这就是您声明多维数组的方式。因此，以下内容：

int [][] winningPositions = {{0,1,2},{3,4,5},{6,7,8},{0,3,6},{1,4,7},{2,5,8},{0,4,8},{2,4,6}};

产生与以下相同的数组：

int[][] winningPositions = new int[8][3];
winningPositions[0][0] = 0;
winningPositions[0][1] = 1;
winningPositions[0][2] = 2;
...
winningPositions[7][0] = 2;
winningPositions[7][1] = 4;
winningPositions[7][2] = 6;

到目前为止和我在一起吗？

完整的“ winningPositions”变量是类型为array的对象，其内容本身是数组序列。好吧，所以现在当您执行循环时，您不了解的是：

for (int [] winningPosition : winningPositions)

“ winningPosition”数组中的每个项目本身都是一个数组-正如我刚才所说的-因此，“一个对象”解析为内部数组，该数组具有3个元素，而外部数组具有8个元素。

有帮助吗？

附带说明：这样的代码要么针对新程序员，要么由不懂OO编程的人编写。有必要了解它是如何工作的，它不一定要被模仿。或者至少在您知道我对此有误的时候，您就会知道我为什么错了。

Answer 2

for (int [] winningPosition : winningPositions)

遍历名为winningPositions的数组。每次迭代都有一个名为winningPosition的变量，它是一个长度为3的整数数组。

if (gameState[winningPosition[0]] == gameState[winningPosition[1]] &&
    gameState[winningPosition[1]] == gameState[winningPosition[2]] &&
    gameState[winningPosition[0]] != 2)

检查所有位置是否都由同一玩家拥有，最后一部分gameState[winningPosition[0]] != 2检查该行是否为空。

编辑：

@ChrisParker在评论中很好地解释了这一行。 for (int [] winningPosition : winningPositions)

Answer 3

for循环正在遍历数组并检查if语句中的每个条件，如果所有条件都为true，则代码将进入IF循环内部，否则将跳过并继续。

欢呼

数组在此代码中起什么作用？

3 个答案: