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Thread: Storing a string in a 2D array

  1. #1
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    Default Storing a string in a 2D array

    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!
    Last edited by namesnipe; September 24th, 2014 at 11:15 PM. Reason: Added link to assignment


  2. #2
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    Default Re: Storing a string in a 2D array

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

  3. #3
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    Default Re: Storing a string in a 2D array

    That also works. Unfortunately, my other problem still exists Thanks though!

  4. #4
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    Default Re: Storing a string in a 2D array

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

  5. #5
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    Default Re: Storing a string in a 2D array

    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;
    }

  6. #6
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    Default Re: Storing a string in a 2D array

    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.

  7. #7
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    Default Re: Storing a string in a 2D array

    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

  8. #8
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    Default Re: Storing a string in a 2D array

    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

  9. #9
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    Default Re: Storing a string in a 2D array

    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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