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Thread: [HELP] Iterating through a jagged edged array

  1. #1
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    Default [HELP] Iterating through a jagged edged array

    Hi everyone,

    Just found this forum (thanks google) and was pleased to see there was a section dedicated to collections and generics..

    I need some help with an iteration. I have an array of arrays, something like this:

    String [][]variations = new String[6][];

    Now for each of the arrays stored in this array, the length isn't known until runtime (because the values are stored from values in a database)..

    At the moment, I'm testing the iterations on a set that looks something like this:

    variations[0].length = 1;
    variations[1].length = 1;
    variations[2].length = 1;
    variations[3].length = 4;
    variations[4].length = 2;
    variations[5].length = 1;

    What I am trying to achieve, is to iterate through this array of arrays, and produce a string of all possible combinations. Using the set above, there are 8 different possible combinations, something like this:

    [1a][2a][3a][4a][5a][6a]
    [1a][2a][3a][4a][5b][6a]
    [1a][2a][3a][4b][5a][6a]
    [1a][2a][3a][4b][5b][6a]
    [1a][2a][3a][4c][5a][6a]
    [1a][2a][3a][4c][5b][6a]
    [1a][2a][3a][4d][5a][6a]
    [1a][2a][3a][4d][5b][6a]

    I hope this is making sense..

    Anyway, does anyone know an easy way to do this? This is the code I'm using at the moment.. It works prefectly but it's pretty messy..

    for (int la = 0; la < variations[0].length; la++) {
    					for (int lb = 0; lb < variations[1].length; lb++) {
    						for (int lc = 0; lc < variations[2].length; lc++) {
    							for (int ld = 0; ld < variations[3].length; ld++) {
    								for (int le = 0; le < variations[4].length; le++) {
    									for (int lg = 0; lg < variations[5].length; lg++) {
    										StringBuffer sb = new StringBuffer();
    										sb.append(variations[0][la]);
    										sb.append(";");
    										sb.append(variations[1][lb]);
    										sb.append(";");
    										sb.append(variations[2][lc]);
    										sb.append(";");
    										sb.append(variations[3][ld]);
    										sb.append(";");
    										sb.append(variations[4][le]);
    										sb.append(";");
    										sb.append(variations[5][lg]);
    										System.out.println(sb);
    									}
    								}
    							}
    						}
    					}
    				}
    			}

    Thanks.


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: [HELP] Iterating through a jagged edged array

    A 2-D array in java is just an array of arrays. So, if you get each single array you can reduce the 2D problem down to a 1D problem:

    int[][] example = new int[5][];
    // create a jagged array
    int[0] = {1,2,3,4,5};
    int[1] = {6,7,8};
    int[2] = {9,10,11,12};
    int[3] = {13,14,15,16,17,18,19,20};
    int[4] = {21};
     
    for (int i = 0; i < example.length; i++)
    {
         for (int j = 0; j < example[i].length; j++)
         {
              System.out.println("At example[" + i + "]["+j+"]: " + example[i][j]);
         }
    }

  3. #3
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    Default Re: [HELP] Iterating through a jagged edged array

    Hi, thanks for the reply, however this is not the issue.

    I have googled a lot for the solution to my problem, and I see the same method suggested everywhere.

    The problem is that I want to go through each row, and create a string with 1 string from each row, but there should be x different strings produced depending on how many strings are in each array.

    Like so:

    Array1String1 + Array2String1 + Array3String1...
     
    Array1String2 + Array2String1 + Array3String1...
     
    Array1String1 + Array2String2 + Array3String1...

    And so on.. for now I've found a good enough solution but if you can produce a simple and quick alternative I would be very grateful.

    Cheers.

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