How to convert a ArrayList into 2D array in Java 7

Question

I am trying to convert a Integer list in a 2D array in java 7. I first converted a String list to Integer and then Integer list to 2D array. Then I will do more operations as required. What I tired is

List<String> list = Arrays.asList("1110", "1010", "1011", "1110");
    List<Integer> intList = new ArrayList<>();
    for (String s : list) {
        intList.add(Integer.valueOf(s));
    }
    //the problem is from here
    int[][] array = new int[intList.size()][];
    for (int i = 0; i < list.size(); i++) {
        for (int j = 0; j < list.size(); j++) {
            array[i][j] = intList.get(j + (list.size() * i));
        }
    }

I tried solving my issue looking at this Converting an ArrayList into a 2D Array and this Convert ArrayList into 2D array containing varying lengths of arrays but majority of the answers are given in java 8 which I don't want! i know its a basic problem but i am stuck! Can someone help me to fix this? Thanks in advance!

The resulting 2D array should be like

1110

1010

1011

1110

What is the condition behind 1D to 2D ? Give an example in you post — Eklavya, Jul 25 '20 at 15:57
[edit] your question and post the resulting 2D array that you want to get from the example list in your question. — Abra, Jul 25 '20 at 15:58
The example you give at the end doesn't look like a 2D array. — Brian McCutchon, Jul 25 '20 at 16:07
Every string represent 1D array ? means `{1,1,1,0}{1,0,1,0}` ...? — Eklavya, Jul 25 '20 at 16:11
It will certainly look like a 2d array if you write them in separate lines! — Rajnish Sharma, Jul 25 '20 at 16:11
Yes @User-Upvotedon'tsayThanks you got my point! Strings which are present in my list represents 1d array! — Rajnish Sharma, Jul 25 '20 at 16:14
@CodeDexter `1110` seems like a single integer and you are doing operation like `Integer.valueOf(s)` for `1110` that also makes confusion. You can update your question with an example for this. — Eklavya, Jul 25 '20 at 16:20

Eklavya · Accepted Answer · 2020-07-25T16:22:02.193

2

You can use .charAt() to get the character of the position in every string.

List<String> list = Arrays.asList("1110", "1010", "1011", "1110");
int[][] array = new int[list.size()][list.get(0).length()];
for (int i = 0; i < list.size(); i++) {
    for (int j = 0; j < list.get(i).length(); j++) {
        array[i][j] = list.get(i).charAt(j)-'0';
    }
}

edited Jul 25 '20 at 16:22

answered Jul 25 '20 at 16:14

Eklavya

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How to convert a ArrayList into 2D array in Java 7

1 Answers1