/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	private static Random generator = new Random();
 
	public static void main (String[] args) throws java.lang.Exception
	{
		double[][] mainArray = new double[7][8];
		for (int i = 0; i < mainArray.length; i++) {
        	for(int j = 0; j < mainArray[i].length; j++) {
            	mainArray[i][j] = generator.nextInt(255);
        	}
        	System.out.println(Arrays.toString(mainArray[i]));
    	}
    	System.out.println();
    	System.out.println();
 
    	List<double[][]> l = chunks(mainArray, 2);
    	for (double[][] chunk : l) {
    		for (double[] row : chunk) {
    			System.out.println(Arrays.toString(row));
    		}
    		System.out.println();
    	}
	}
 
	public static List<double[][]> chunks(double [][]larger, int chunksize) throws 
		ArrayIndexOutOfBoundsException, NullPointerException  {
    	if (chunksize <= 0)
        	throw new ArrayIndexOutOfBoundsException("Chunks must be atleast 1x1");
    	int size = larger.length / chunksize * (larger[0].length / chunksize);
    	List<double[][]> subArrays = new ArrayList<>();
 
    	for (int c = 0; c < size; c++) {
        	double[][] sub = new double[chunksize][chunksize];
        	int startx = (chunksize * (c / chunksize)) % larger.length;
        	int starty = (chunksize * c) % larger[0].length;
 
        	if (starty + chunksize > larger[0].length) {
        		starty = 0;
        	}
        	if (startx + chunksize > larger.length) {
        		continue;
        	}
 
        	for (int row = 0; row < chunksize; row++) {
            	for (int col = 0; col < chunksize; col++) {
                	sub[row][col] = larger[startx + row][col + starty];
            	}
        	}
        	subArrays.add(sub);
    	}
 
    	return subArrays;
	}
}

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