Java 2D array program help please?

Question

Hi - I'm teaching computer science to myself (java, using jGRASP) using some websites online, and one of the activities I have to do is to make an "image smoother" program.
I just started learning about 2D array, and I think I get what it is (based on what I know of 1D arrays), but I have no clue how to do this activity.
This is what the description says:
"A grey-level image is sometimes stores as a list of int values. The values represent the intensity of light as discrete positions in the image.
An image may be smoothed by replacing each element with the average of the element's neighboring elements.
Say that the original values are in the 2D array "image". Compute the smoothed array by doing this: each value 'smooth[r][c]' is the average of nine values:
image [r-1][c-1], image [r-1][c ], image [r-1][c+1],
image [r ][c-1], image [r ][c ], image [r ][c+1],
image [r+1][c-1], image [r+1][c ], image [r+1][c+1].
Assume that the image is recangular, that is, all rows have the same number of locations. Use the interger arithmetic for this so that the values in 'smooth' are integers".
and this is what the website gives me along with the description above:
import java.io.*;
class Smooth
public static void main (String [] args) throws IOException
int [][] image = {{0,0,0,0,0,0,0,0,0,0,0,0,},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,5,5,5,5,5,5,5,5,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0}};
//assume a rectangular image
int[][] smooth = new int [image.length][image[0].length];
//compute the smoothed value for
//non-edge locations in the image
for (int row=1; row<image.length-1; row++)
for (int col=1; col<image[row].length-1; col++)
smooth[row][col] = sum/9;
//write out the input
//write out the result
"The edges of the image are a problem because only some of the nine values that go into the average exist. There are various ways to deal with this problem:
1. Easy (shown above): Leave all the edge locations in the smoothed image to zero. Only inside locations get an averaged value from the image.
2. Harder: Copy values at edge locations directly to the smoothed image without change.
3. Hard: For each location in the image, average together only those of the nine values that exist. This calls for some fairy tricky if statements, or a tricky set of for statements inside the outer two.
Here is a sample run of the hard solution:
c:\>java ImageSmooth
input:
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 5 5 5 5 5 5 5 5 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
output:
0 0 0 0 0 0 0 0 0 0 0 0
0 0 1 1 1 1 1 1 1 1 0 0
0 1 2 3 3 3 3 3 3 2 1 0
0 1 3 5 5 5 5 5 5 3 1 0
0 1 3 5 5 5 5 5 5 3 1 0
0 1 3 5 5 5 5 5 5 3 1 0
0 1 3 5 5 5 5 5 5 3 1 0
0 1 3 5 5 5 5 5 5 3 1 0
0 1 3 5 5 5 5 5 5 3 1 0
0 1 2 3 3 3 3 3 3 2 1 0
0 0 1 1 1 1 1 1 1 1 0 0
0 0 0 0 0 0 0 0 0 0 0 0
c:\>"
OKAY that was very long, but I'm a beginner to java, especially to 2D arrays. If anyone could help me with this step-by-step, I would greatly appreciate it! Thank you very much in advance!

Answer 1

larissa. wrote:
I did try, but I have no clue where to start from. That's why I asked if someone could help me with this step by step...regardless, our track record for helping folks who state they are "completely lost" or "don't have a clue" is poor to dismal as there is only so much a forum can do in this situation. We can't put knowledge in your head; only you can do that. Often the best we can do is to point you to the most basic tutorials online and suggest that you start reading.
That being said, perhaps we can help you if you have some basic knowledge here, enough to understand what we are suggesting, and perseverance. The first thing you need to do is to try to create this on your own as best you can, then come back with your code and with specific questions (not the "I'm completely lost" kind) that are answerable in the limited format of a Java forum. By posting your code, we can have a better idea of just where you're making bad assumptions or what Java subjects you need to read up on in the tutorials.