How to copy a mat object to a integer 2D matrix in opencv java ?

edit

I want it to convert or copy as int[][] format

can you explain, why this would be nessecary ? (and what for ?)

Now I want to see the pixel values of mat object

System.out.println(mat.dump());

I have to convert a grayscale matrix to a 2D integer array( or matrix) so that I can do some Operation on that matrix (which I got from image) and get some different images back again from that output matrix. Previously I was doing with a random large sized matrix but now have to do with the matrix from grayscale image. That is the reason I want to convert it to a 2D matrix with row col.

Previously I was working with random 128*!28 matrix. Bu now I have to work with the matrix i got from that grayscale image. I want to pass this matrix from image as argument but unable to do so. Please suggest.

public static void main(String[] args) { //int row,col=128; //int[][] mat = new int[row][col];

    System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
    Imgcodecs imageCodecs = new Imgcodecs();
    String file ="Image file path"; 
    Mat image = imageCodecs.imread(file, Imgcodecs.IMREAD_GRAYSCALE);  
    System.out.println("Image Loaded");  
    System.out.println(image.dump());

    int row=image.rows();
    int col=image.cols();

     for (int i = 1; i < row-1; i++) { 
      for (int j = 1; j < col-1; j++) {
             //subMatrix(i, j, mat);
              submatrix(i,j,image);}

Posting the remaining code below :

public class SampleImage {

 //public static void subMatrix(int startRow, int startCol, int[][] mat) {
public static void subMatrix(int startRow, int startCol,  mat image) {

           int[][] sub = new int[3][3];
    System.out.print("Submatrix for : ");
    System.out.println(startRow + ", " + startCol + " is : ");     
    for (int i = 0; i < 3; i++) {
     for (int j = 0; j < 3; j++) {

         //sub[i][j] = mat[i+(startRow-1)][j+(startCol-1)]; 
         sub[i][j] = image[i+(startRow-1)][j+(startCol-1)]; //Traversing a 3*3 matrix in large matrix 

                     }
                 }

             MultMatrix(startRow,startCol,sub);
            BitMatrix(startRow,startCol,sub);

so that I can do some Operation

what exactly ? why not use opencv for this, too ?