Array to row on 2D List/ArrayList Java

Question

I'm wanting to create a 2D array with a set amount columns (5) but an indefinite amount of rows. It was suggested to use a list with an arraylist like so List<List<String>> _upload = new ArrayList<List<String>>(); However this doesn't give me my 5 set columns I need.

My second problem is the way I'm feeding data into this 2D array. I'm given an array of information (5 long to fit a row) String[] _ToUpload = {"One", "Two","Three","Four","Five"};. How would go about implementing a method that created a new row and merged that array into the row of the 2D array.

New to Java so sorry if this seems a dumb question. Many thanks

You should try to write your own data structure. List<List<Type>> doesnt implement 2d matrix, it implements list of lists. — Everv0id
– Everv0id, Commented Mar 22, 2015 at 15:42
Do the 5 columns have different meanings (e.g. first name, surname, age, height, weight)? If so, you should write a class to represent that data and then use an ArrayList<MyClass>. — Paul Boddington
– Paul Boddington, Commented Mar 22, 2015 at 15:44
Yes, the five columns have different meanings. How would I go about this? — Tom Carter
– Tom Carter, Commented Mar 22, 2015 at 15:50

Adeel Ahmad · Accepted Answer · 2015-03-22 15:46:35Z

1

Try this(I haven't tested it) :

// create an list named arrayList and add elements to the list
    String[][] array = new String[arrayList.size()][];
    for (int i = 0; i < arrayList.size(); i++) {
        ArrayList<String> row = arrayList.get(i);
        array[i] = row.toArray(new String[row.size()]);
    }

answered Mar 22, 2015 at 15:46

Adeel Ahmad

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