Android: Two dimensional ArrayList Help

Question

Currently I have my code putting user input into a one-dimensional ArrayList, but I would like to put them into a two dimensional ArrayList and am having some trouble.

Here is my code:

public class Game extends Activity implements OnClickListener {
   private static final String TAG = "Matrix";
   static ArrayList<EditText> columnEditTexts;




   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       this.setContentView(R.layout.matrix);
       View doneButton = findViewById(R.id.done_button);
       doneButton.setOnClickListener(this);
       columnEditTexts = new ArrayList<EditText>();

       for(int i = 0; i < MatrixMultiply.h1; i++){
           TableLayout table = (TableLayout)findViewById(R.id.myTableLayout);
           TableRow row = new TableRow(this);
           EditText column = new EditText(this);
           for(int j = 0; j < MatrixMultiply.w1; j++){
               table = (TableLayout)findViewById(R.id.myTableLayout);
               column = new EditText(this);
               column.setId(i);
               row.addView(column);
               columnEditTexts.add(column);
           }
           table.addView(row);
       }



   }

Right now it's only putting the EditTexts into a single dimension array. How would I put them into a two dimensional array? — Biggsy
– Biggsy, Commented Mar 3, 2011 at 4:23
Could you add to the question what you hope to achieve by storing these in a two dimensional array? — Corey Sunwold
– Corey Sunwold, Commented Mar 3, 2011 at 4:32
Ultimately I would like to Multiply two matrices together (for example roseindia.net/java/beginners/MatrixMultiply.shtml). I have another activity for the second matrix that is just like this one and then a results activity. — Biggsy
– Biggsy, Commented Mar 3, 2011 at 4:43

Corey Sunwold · Accepted Answer · 2011-03-03 19:51:24Z

9

Well you need to first create a two dimensional ArrayList. To do that, you need to create an ArrayList of ArrayLists.

ArrayList<ArrayList<EditText>> arrayOfEditTexts = new ArrayList<ArrayList<EditText>>();

So then you loop will become something along these lines (assuming I understand what you are trying to do):

for(int i = 0; i < MatrixMultiply.h1; i++){
       columnEditTexts = new ArrayList<EditText>();
       TableLayout table = (TableLayout)findViewById(R.id.myTableLayout);
       TableRow row = new TableRow(this);
       EditText column = new EditText(this);
       for(int j = 0; j < MatrixMultiply.w1; j++) {               
           column = new EditText(this);
           column.setId(i);
           row.addView(column);
           columnEditTexts.add(column);
       }
       table.addView(row);
       arrayOfEditTexts.add(columnEditTexts);
   }

edited Mar 3, 2011 at 19:51

answered Mar 3, 2011 at 4:31

Corey Sunwold

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2 Comments

Biggsy Over a year ago

This is close but seems to keep adding identical ArrayLists. For a 2x3 matrix I would like the ArrayList to be [1 2 3] [4 5 6]. Currently it is storing it as [1 2 3 4 5 6] [1 2 3 4 5 6]

Corey Sunwold Over a year ago

There is a problem in your for loop then. The structure of the ArrayList remains the same, the problem is in how you populate it.

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