Getting access to an ArrayList within an ArrayList

Question

I'm sure the first response will be 'wtf, don't use arraylists!', but I'm really just trying to get this working in any way that I can.

It's basically the 'match looker' for a match 3 game. I'm having trouble getting access to the match data within the match list. See below..

    public void FindAndRemoveMatches() {

    ArrayList foundMatches = LookForMatches();

    //just checking if we're getting the right amount for now
    Debug.Log("We found " + foundMatches.Count + " 'Match 3's");

    foreach(Object el in foundMatches){
       //   Debug.Log(el.ToString());
    }

}

ArrayList LookForMatches(){

    //List<int> matchList = new List<int>();
    ArrayList matchList = new ArrayList();

    // search for horizontal matches
    // note that we're subtracting two rows here.
    // We don't need to check the last two rows because we're matching 3.
    for (int i = 0; i < BOARD_WIDTH; i++){
        for (int j = 0; j < BOARD_HEIGHT-2; j++){
            ArrayList match = GetMatchHoriz(i,j);
            if (match.Count > 2) {
                matchList.Add(match);
                i += match.Count-1;
            }
        }
    }

    // search for vertical matches
    for (int i = 0; i < BOARD_WIDTH; i++){
        for (int j = 0; j < BOARD_HEIGHT-2; j++){
            ArrayList match = GetMatchVert(i,j);
            if (match.Count > 2) {
                matchList.Add(match);
                j += match.Count-1;
            }

        }
    }


    return matchList;
}


// look for horizontal matches starting at this point
ArrayList GetMatchHoriz(int col,int row){
    ArrayList match = new ArrayList();
    match.Add(mBoard[col,row]);

    for(int i = 1; (col+i)<8; i++) {
        if (mBoard[col,row] == mBoard[col+i,row]) {
            if(mBoard[col+i,row] > mPieces.GetNumPieceTypes()) match.Add(mBoard[col+i,row]);
        } else {
            return match;
        }
    }
    return match;
}   

// look for horizontal matches starting at this point
ArrayList GetMatchVert(int col,int row){
    ArrayList match = new ArrayList();
    match.Add(mBoard[col,row]);

    for(int i = 1; (row+i)<8; i++) {
        if (mBoard[col,row] == mBoard[col,row+i]) {
            if(mBoard[col,row+i] > mPieces.GetNumPieceTypes()) match.Add(mBoard[col,row+i]);
        } else {
            return match;
        }
    }
    return match;
}

Good news is, I know that it's finding the matches correctly. The number of matches it's finding using the debug log correlates with what's happening on the screen. Yay! But, I need to get access to that data so I can compare it to the board (mBoard[col,row]) and remove those objects from the game board.

The 'foreach' loop in findandremovematches gives an error about casting. Any help with this?

thanks!

It would help to have the exact error message.

Greg Fenton
– Greg Fenton

2012-04-04 19:12:05 +00:00
Commented Apr 4, 2012 at 19:12 — Greg Fenton
– Greg Fenton, Commented Apr 4, 2012 at 19:12
You were wrong about the first response :)

Gert Arnold
– Gert Arnold

2012-04-04 19:14:41 +00:00
Commented Apr 4, 2012 at 19:14 — Gert Arnold
– Gert Arnold, Commented Apr 4, 2012 at 19:14
Possible duplicate of C# Array List of ArrayList

Jim Fell
– Jim Fell

2016-05-12 20:31:30 +00:00
Commented May 12, 2016 at 20:31 — Jim Fell
– Jim Fell, Commented May 12, 2016 at 20:31

ata · Accepted Answer · 2012-04-04 19:22:32Z

2

I hope i understand your question correctly

foreach(Objecct obj in list)
{
 ArrayList inner = obj as ArrayList;
 if(inner != null)
 {
  //this is what you are looking for
  //you can then iterate the inner array list and get the int[,] you saved
 }
}

However, as suggested, use List<ArrayList> or List<List<int[,]>> if I guessed it right.

answered Apr 4, 2012 at 19:22

ata

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Comments

Servy · Accepted Answer · 2012-04-04 19:22:46Z

2

If you're using ArrayLists because you think they're easier, don't. Use List. If you're using ArrayLists because you have to and there is no way for you to use List (which I doubt) then you'll have something like this:

foreach(ArrayList innerList in foundMatches)
{
  foreach(SomeClassThatYouAddToInnerLists item in innerlist)
  {
    //use item;
  }
}

Replace SomeClassThatYouAddToInnerLists with whatever the type is that you're adding to the inner ArrayLists. (The type of mBoard.)

If you use Lists then it's very clear what the type is of everything inside of the list. A List<List<int>> is easy to work with. It's a list of lists of numbers.

answered Apr 4, 2012 at 19:22

Servy

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