Storing a string in a 2D array

**namesnipe** · September 24th, 2014, 09:43 PM

Hi!

Edit: Link to my assignment: Programming Challenges-Graphical Editor

One of the requirements of my programming assignment is that a user enters a command along with two numbers. For example, if I entered the following command:

I 5 6

The program create an image like this (it wouldn't be outputted though):

00000
00000
00000
00000
00000
00000

It creates a 5 x 6 "image". This is where my troubles begin. The program should also accepts other commands, such as:

L 3 2 F

which would produce (also not outputted):

00000
00F00
00000
00000
00000
00000

Here is my method for creating an "image" with an M * N array

for (int i = 0; i < column; i++)
{
    for (int j = 0; j < row; j++)
    {
        System.out.print("0");
    }
    System.out.println();
}

The code works, but I need to store the image in an array so it can be changed by other methods (I can't create the image manually every time). I tried doing something like this but it doesn't work:

public static String[][] createImage(int row, int column)
{        
    String[][] image = new String[row][column];
    for (int i = 0; i < column; i++)
    {
        for (int j = 0; j < row; j++)
        {
            image[j][i] = "0";
        } 
        System.out.println();
    }
    return image;
}

This method outputs as many blank lines as the columns I entered and the memory location of image.

So my question is: how would I store "0" in a 2D array so that it can be accessed and changed by other methods?
Or, am I using a 2D array incorrectly and will the image have to be created manually every time? If so, how would I output image if it is created in a separate method?

Thank you!

**camel-man** · September 24th, 2014, 09:47 PM

How about a 2d array of characters. That way you could say image[i][j] = '0';

**namesnipe** · September 24th, 2014, 09:59 PM

That also works. Unfortunately, my other problem still exists

Thanks though!

**camel-man** · September 24th, 2014, 10:00 PM

What is your other problem? You should be able to accomplish all that you listed with this 2d char array

**namesnipe** · September 24th, 2014, 10:08 PM

When I try to call createImage, it returns a number of blank lines (same as the columns I enter) along with its memory location. This is my updated createImage method, by the way.

public static char[][] createImage(int row, int column)
{        
    char[][] image = new char[row][column];
    for (int i = 0; i < column; i++)
    {
        for (int j = 0; j < row; j++)
        {
            image[j][i] = '0';
        }
        System.out.println();
    }
    return image;
}

**camel-man** · September 24th, 2014, 10:20 PM

Well, you arent printing anything... you're just printing a new line. you should print out the actual image slot..

  for (int i = 0; i < column; i++)
		    {
		        for (int j = 0; j < row; j++)
		        {
		            image[j][i] = '0';
		            System.out.printf("%c ", image[j][i]);
		        }
		        System.out.println();
		    }

I might be confused on what you actually want the method to achieve.

**namesnipe** · September 24th, 2014, 11:13 PM

It worked! Thanks! Before I continue, this assignment is actually a programming challenge from a website. If you want, you can take a look at it here: Programming Challenges-Graphical Editor

I looked through the requirements once again and the image is only outputted when the user enters the S command. So if I created a 5 by 6 image with the I command, then replaced the 3rd pixel in the 2nd row, I would only output the new image. That's what I'm not sure how to do. Sorry if I'm so confusing!

Input:

I 5 6

L 3 2 F

Output:

00000
00000
00000
00000
00000
00000

**camel-man** · September 24th, 2014, 11:16 PM

You should make a method that takes those parameters. Then you can go to that row and column and put in the letter you want manually

**namesnipe** · September 25th, 2014, 04:46 PM

Whenever I print the image, the output also includes the memory location of the array. How can I get rid of that? I've tried Arrays.toString(), but it ouputs the memory location of each column. I've also tried Arrays.deepToString(), but that outs the image like so:

[[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, 0, 0, 0, 0]]

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