如何绕过IndexOutOfBounds错误

Question

所以我有一个我正在使用的2D角色阵列。每个空间可以被“C”，“M”或“N”（意思不重要）占据。我有两个方法，一个检查元素周围的4个空格，另一个检查元素周围的8个空格。这是前者。

public boolean checkAnySpace4(char[][] grid, int x, int y)
    {
        if(grid[x-1][y] == 'N' || grid[x-1][y] == 'M'|| grid[x-1][y] == 'C')
        {
            return false;
        }
        if(grid[x-1][y-1]  == 'N' || grid[x-1][y-1]  == 'M'|| grid[x][y-1]  == 'C')
        {
            return false;
        }
        if(grid[x][y-1]  == 'N' || grid[x][y-1]  == 'M'|| grid[x][y-1]  == 'C')
        {
            return false;
        }
        if(grid[x+1][y]  == 'N' || grid[x+1][y]  == 'M'|| grid[x+1][y]  == 'C')
        {
            return false;
        }
        else 
            return true;
    }

我只是希望方法在任何周围元素（无论是4还是8）已被占用时返回false，如果所有元素都已打开，则返回true。我该怎么做才能得到IndexOutOfBounds错误？

编辑：这是代码的其余部分。

public void start(int steps)
    {
        char [][] grid = new char[25][25];


        int numCells = 0;
        while (numCells < 10) {

            //System.out.println("step = " + i);
            int random = (int)   Math.floor((Math.random() * 24));
            int random2 = (int)  Math.floor((Math.random() * 24));

            if(checkGrid(grid, random, random2) == true) //if current cell is empty
            {
                addCellToGrid(grid, random, random2, 'N');//add cell with different coordinates
                numCells++;
            }
        }

        printGrid(grid);

        System.out.print("exiting before steps");
        //System.exit(-1);
        /*
         * Fix array index out of bounds error
         * 
         */



        for(int i = 0; i < steps; i++)//populate array
        {



            for(int j = 0; j < 25; j++)
            {
                for(int k = 0; k < 25; k++)
                {
                    if(new Random().nextDouble() <= (1-e)) //probability that cell dies
                    {
                        die(grid, j, k);
                        continue;
                    }

                    else ////if not dead, mutate with prob p_n for N,M cells, p_c for C cells
                    {
                        if(new Random().nextDouble() <= m) //mutate with prob m
                        {
                            mutate(grid, j,k);//mutate cell

                                if(grid[j][k] == 'N' || grid[j][k] == 'M')//if cell is type N or M
                                {
                                    if(checkAnySpace4(grid, j, k))//if cell has space to divide
                                    {
                                        if(new Random().nextDouble() <= p_n)//divide with probability p_n
                                        {
                                            divide(grid, j, k);//divide cell
                                        }
                                    }
                                    else
                                    {
                                        continue; //cell does not divide, do nothing
                                    }
                                }
                            }
                             if(grid[j][k] == 'C')//C grid[j][k]s cannot mutate
                            {
                                if(checkAnySpace8(grid, j, k))//if cell has space to divide
                                {
                                    if(new Random().nextDouble() <= p_c)//divide with probability p_c
                                    {
                                        divide(grid, j, k);//divide cell
                                    }
                                }
                            }   
                        }    
                }           
            }
        }    

    printGrid(grid);    
    }

在checkAnySpace4方法的第一个if语句中抛出错误。

Answer 1

在函数中再添加两个变量：size_x和size_y到函数。

然后：

public boolean checkAnySpace4(char[][] grid, int x, int y, int size_x, int size_y)
{
    if(x == 0 || y == 0 || x == size_x || y == size_y){
        /*complain on the console or raise an exception*/
        return false;
    }

    if(grid[x-1][y] == 'N' || grid[x-1][y] == 'M'|| grid[x-1][y] == 'C')
    {
        return false;
    }
    if(grid[x-1][y-1]  == 'N' || grid[x-1][y-1]  == 'M'|| grid[x][y-1]  == 'C')
    {
        return false;
    }
    if(grid[x][y-1]  == 'N' || grid[x][y-1]  == 'M'|| grid[x][y-1]  == 'C')
    {
        return false;
    }
    if(grid[x+1][y]  == 'N' || grid[x+1][y]  == 'M'|| grid[x+1][y]  == 'C')
    {
        return false;
    }
    else 
        return true;
}

您可能需要从size_x和size_y中减去1。