Java integer array with dynamic size

Question

I am trying to use an integer array. Now, there are a couple of things;

I cannot initialize the size during initialization as it depends on some other condition (can be 1,2,5 elements, etc)

I want to iterate over it & perform some operation. However, I do know for sure those would be integer elements always

So, my question is how can I initialize the array in this case ?

int[] dynamicSizeArr = new int[0];

switch (someVar) {
    case "A":
        dynamicSizeArr = new int[] { 5,10,15,20,25};
        break;
    case "B":
        dynamicSizeArr = new int[] { 10,20};
        break;
    case "C":
        dynamicSizeArr = new int[] { 10};
        break;
    default:
        break;
}

for (int i = 0; i < dynamicSizeArr.length; i++) {
    x.insert(dynamicSizeArr[i] + i, '.');
}

Personally I would do int[] dynamicSizeArr = null; but the OP code should work — Scary Wombat
– Scary Wombat, Commented Nov 21, 2019 at 4:57
@ElliottFrisch; I have initialized it with size 0 (new int[0])...I am not sure if that is standard and then I keep on assigning it dynamically like dynamicSizeArr = new int[] { 10,20}, etc — copenndthagen
– copenndthagen, Commented Nov 21, 2019 at 5:00
ArrayList is the standard way to have a dynamically sized array in Java. By definition, using a primitive array in this way is unusual. However, it's not wrong. If your switch were in a method that you call, then it wouldn't even be that unusual. — Elliott Frisch
– Elliott Frisch, Commented Nov 21, 2019 at 5:03
I would say initializing int[] dynamicSizeArr = {}; would be more natural. — Leni
– Leni, Commented Nov 21, 2019 at 5:27

Varun Mukundhan · Accepted Answer · 2019-11-21 04:58:31Z

3

Use java.util.ArrayList in that case.

ArrayList<Integer> arr = new ArrayList<Integer>();
int n = 5;
//n can be anything
for (int i=0; i<n; i++) 
       arr.add(i);

answered Nov 21, 2019 at 4:58

Varun Mukundhan

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