JAVA : how to check if an arraylist of 1D arrays

i'm a student in my 1st year, and i need to check if an arrayList of 1D array had a value in index 0, if so i need to keep that value of index 0, and update its value of order [0,1].

What I have tried:

<pre>i created first my 1D array as int [] Order = new int [2];

is a getOrder() methode. asking the user (Server in this case) to add integers ( id of product) and second time to add number of how many pruducts.

and add : Order = {idConso, nbrConso}

than i call the methode from my main(), and passing an arrayList (ord) as a parametre to store the the Orders.

But, when i print the ord ( arrayList of 1D Order array), i shouldn't have the same idConso twice in it.

which means, i need to find a way to check if the idConso (id of the product) is already in ord ( arrayList ) and is so, i need just to check if the arrayList has already idConso and keep it but add the nbrConso (numnbre of orders of that product).

i hope its clear :( thank you.