ArrayAverager.java

public class ArrayAverager {

    public static int[][] makeAvArray(int[][] theArray) {
        int rows = theArray.length;
        int cols = theArray[0].length;
        int[][] avArray = new int[rows][cols];

        int sum;
        int neighbours;

        for (int r=0; r<rows; r++) {
            for (int c=0; c<cols; c++) {
                sum = theArray[r][c];
                neighbours = 1; // itself
                if (c>0) {
                    sum += theArray[r][c-1];
                    neighbours++;
                    if (r>0) {
                        sum += theArray[r-1][c];
                        sum += theArray[r-1][c-1];
                        neighbours+=2;
                    }
                    if (r<rows-1) {
                        sum += theArray[r+1][c];
                        sum += theArray[r+1][c-1];
                        neighbours+=2;
                    }
                } // if c
                if (c<cols-1) {
                    sum += theArray[r][c+1];
                    neighbours++;
                    if (r>0) {
                        sum += theArray[r-1][c];
                        sum += theArray[r-1][c+1];
                        neighbours+=2;
                    }
                    if (r<rows-1) {
                        sum += theArray[r+1][c];
                        sum += theArray[r+1][c+1];
                        neighbours+=2;
                    }
                } // if c
                avArray[r][c] = sum/neighbours;
            } // for c
        } // for r

        return avArray;

    } // makeAvArray()

    public static void displayArray(int[][] array) {
        for (int r=0; r<array.length; r++) {
            for (int c=0; c<array[0].length; c++) {
                System.out.print(array[r][c]+" ");
            } // for c
            System.out.println();
        } // for r
    } // displayArray()

    public static void main(String[] args) {
        final int ROWS = 3;
        final int COLS = 4;
        int[][] array = new int[ROWS][COLS];

        int n=1;
        // for test example, number in ascending order
        for (int r=0; r<ROWS; r++) {
            for (int c=0; c<COLS; c++) {
                array[r][c] = n++;
            } // for c
        } // for r

        System.out.println("Original array:\n");
        displayArray( array);
        System.out.println("\nArray of averages:\n");
        displayArray( makeAvArray( array));
    } // main()

} // class ArrayAverager