我想從中間元素（第 2 行，第 2 列）的 (1,1) 起始位置遍歷一個大 7*7 矩陣內的 3*3 子矩陣。位置 (1,1) 對應的子矩陣將是                [(0,1),(0,2),(0,3)]                 [(1,1),(1,2),(1,3)]                 [(2,1),(2,2),(2,3)]像這樣遍歷將繼續..下一個子矩陣起始位置將是 (1,2)                 [(0,2),(0,3),(0,4)]                  [(1,2),(1,3),(1,4)]                  [(2,2),(2,3),(2,4)]我的代碼static int i;static int j;static int g;static int h;static void submatrix(int p,int q,int[][] mat) {System.out.print("Submatrix for : ");System.out.println(p+","+q);shiftmatrix(p,q,mat);}static void shiftmatrix(int p,int q,int[][] mat) { int m,n; int[][] d = new int[3][3]; for( m=0;m<3;m++) {  for( n=0;n<3;n++) {   p=m+(p-1);   q=n+q;   d[m][n]=mat[p][q];     }   }System.out.println("Your 3*3 SubMatrix is : ");    for ( m = 0; m < 3; m++){    for ( n = 0; n < 3; n++){        System.out.print(d[m][n]+"\t");        }         System.out.println();        }}public static void main(String[] args) {    int[][] a = new int[7][7];    int[][] mat = new int[7][7];    for ( i = 0; i < 7; i++)      {       for ( j = 0; j < 7; j++){          Random rand = new Random();           a[i][j] = rand.nextInt(10);          }      }//copying large matrix to another for passing by argument  System.out.println("Copied matrix is : "); for (i = 0; i < 7; i++){     for (j = 0; j < 7; j++){          mat[g][h]=a[i][j];            System.out.print(mat[g][h]+"\t");        }          System.out.println();    }//Here is the 3*3 submatrix traversing starts... for (i=1;i<6;i++) {   for (j=1;j<5;j++) {    int p=i;     int q=j;     submatrix(p,q,mat);     }  }}}運行此代碼時出現錯誤ArrayIndexOutOfBoundsException: -1 請幫忙