Adding int values to ArrayList of int's

Question

I am trying to add int values to an int[] as follows.

 private ArrayList<int []> read_studioConfig(byte[] buf, int boundary, int offset, int num){

    ArrayList<int []> configs_values = new ArrayList<int[]>();

    int readValues = 0;

    int idx = offset;
    for (int i = 0 ;i < num; i++){
         while(idx < boundary && buf[idx] != 0){
             readValues = i;
             idx ++;
         }
         idx ++;

        configs_values.add(readValues);
    }

    return configs_values;
};

But I could not able to do it. I am getting the following error.

error: no suitable method found for add(int) method Collection.add(int[]) is not applicable (argument mismatch; int cannot be converted to int[]) method List.add(int[]) is not applicable (argument mismatch; int cannot be converted to int[])**

I am doing a stupid mistake but can't put finger on it. What am I missing here ?

To wit: right now you're creating an array list of int arrays. — Dave Newton
– Dave Newton, Commented Oct 24, 2019 at 15:13
@ErnieThomason Changing that solves the problem. But I would like to add values arraylist of int arrays — cantona_7
– cantona_7, Commented Oct 24, 2019 at 15:15
Java collections stores objects, not primitive types. To have 2-D arrays, use ArrayList<ArrayList<Integer>> arr = new ArrayList<ArrayList<Integer>>(); — dSanders
– dSanders, Commented Oct 24, 2019 at 15:16

Federico klez Culloca · Accepted Answer · 2019-10-24 15:24:39Z

1

Firstly you're creating a List of Arrays of integers, so that is the reason your code is failing.

I'm not sure why you're trying to do due to your code is a little bit dirty, but here you have my suggestion:

Use List<Integer> configsValue = new ArrayList() rather than ArrayList<int[]>, use interfaces rather than implementations. Also if you don't need to keep direct access even I'd suggest to you to use LinkedList instead ArrayList because the complexity of adding a new element is O(1) against O(n)

Then your code will work, otherwise if you want to return a List<int[]> be aware of you have to create the array before adding it to the collection

edited Oct 24, 2019 at 15:24

Federico klez Culloca

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answered Oct 24, 2019 at 15:19

geeksusma

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1 Comment

cantona_7 Over a year ago

that clears up a lot. I will look into that direction man. Thanks

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