java - 尽管使用 indexInBounds 仍获取 ArrayIndexOutOfBounds

Question

检查并保持程序入站的方法不起作用我不断收到:array IndexOutOfBounds 错误。由于此错误，我无法继续查看我的 Knight's Tour 实际实现是否有效。

import java.util.Arrays;
class KnightsTour {

    static int the_board[][] = new int[8][8];
    int the_tour[][] = new int [8][8];
    int k,moves = 0;
    int x = 0, y = 0; 
    int z, j = 1;
    boolean tour_found, isSafe;

        //fills 2D array with 0's
        public KnightsTour()
        {
            for (int i = 0; i < 8; i++) 
                {
                 for (int r = 0; r < 8; r++) 
                    {
                            the_board[i][r] = 0;
                        }
                }
        }
        /*recursive method, checks how many moves were made if 16 were made tour finished, 
        else if not moves knight checks if the move is valid if not back tracks*/
        public void findTour(int q)
        {
            if(moves == 68)
                {
                    tour_found = true;
                }

            else move(q); 
            if(isSafe == true)
                    {
                        findTour(q++);
                        moves++;
                    }
            else
                if(isSafe == false)
                    {
                        findTour(q*(-1));
                        moves--;
                    }
        }
        //used to keep prevent arrayindexoutofbounds error
        public boolean arrayInBounds(int x, int y)
        { 
        if(x > 8 || y > 8)
                {
                    return false;
                }
            else return true;
        }
        /*move method uses switch statement to decide which move the knight should make
        based on a case number, negative case numbers back track knight. if statement checks
        if the current array element is empty and the index is inbounds*/
        public void move(int a)
        {

            switch (a)
            {
               case 1:
                if(arrayInBounds(x+2, y+1) == true){
                   if(the_board[x+2][y+1] != 0){                          
                        the_board[x+2][y+1]=j;
                            j++;
                        }
                    }
                else isSafe = false;
               case 2:
                if (arrayInBounds(x+1, y+2) == true){
                    if(the_board[x+1][y+2] != 0){               
                            the_board[x+1][y+2]=j;
                            j++;
                        }
                }
                else isSafe = false;
               case 3:
                 if(arrayInBounds(x-1, y+2) == true){
                   if(the_board[x-1][y+2] != 0){           
                            the_board[x-1][y+2]=j;
                            j++;
                        }
                 }
                else isSafe = false;
               case 4:
                if (arrayInBounds(x-2, y+1) == true){
                    if(the_board[x-2][y+1] != 0){           
                            the_board[x-2][y+1]=j;
                            j++;
                        }
                }
                else isSafe = false;
               case 5:
                if(arrayInBounds(x-2, y-1) == true){
                    if(the_board[x-2][y-1] != 0){           
                            the_board[x-2][y-1]=j;
                            j++;
                        }
                }
                else isSafe = false;
               case 6:
                if(arrayInBounds(x-1, y-2) == true){
                        if(the_board[x-1][y-2] != 0){                    
                            the_board[x-1][y-2]=j;
                            j++;
                        }
            }
                else isSafe = false;
               case 7:
                 if(arrayInBounds(x+1, y-2) == true){
                    if(the_board[x+1][y-2] != 0){          
                            the_board[x+1][y-2]=j;
                            j++;
                        }
                 }
                 else isSafe = false;
               case 8:
                if(arrayInBounds(x+2, y-1) == true){
                 if(the_board[x+2][y-1] != 0){
                            the_board[x+2][y-1]=j;
                            j++;
                        }
                }
                else isSafe = false;
               case -1:
                 the_board[x-2][y-1]=0;
                      j--;
               case -2:
                 the_board[x-1][y-2]=0;
                      j--;
               case -3:
                 the_board[x+1][y-2]=0;
                      j--;
               case -4:
                 the_board[x+2][y-1]=0;
                      j--;
              case -5:
                 the_board[x+2][y+1]=0;
                      j--;
               case -6:
                 the_board[x+1][y+2]=0;
                      j--;
               case -7:
                 the_board[x-1][y+2]=0;
                      j--;
               case -8:
                 the_board[x-2][y+1]=0;
                      j--;
                }

        }
        //for loop to display tour once found//         
        public void displayTour()
        {
            int v = 1;
            for (int i = 0; i < 8; i++) 
                {
                 for (int e = 0; e < 8; e++) 
                    {               
                                if(v % 8 == 0)
                                {
                                    System.out.print(the_board[i][e] + "\t");
                                    System.out.println("\n");
                                } 
                        else    
                            System.out.print(the_board[i][e] + "\t");
                            v++;                
                        }
                }

        }

}

Answer 1

您的arrayInBounds 方法不正确。 8 是无效索引，但您的方法会错误地将其报告为有效。此外，它不会检查 0 以下的无效索引。

更改方法以检查 x 或 y 是否大于 或等于 8，并且还要检查其中一个是否小于 0。