Design Dynamic Array (Resizable Array) Solution

class DynamicArray{
    private ArrayList<Integer> arrayList;
    private int capacity;

    public DynamicArray(int capacity){
        if(capacity <=0){
            throw new IllegalArgumentException("Capacity must be greater than 0.");
        }
        this.arrayList = new ArrayList<>(capacity);
        this.capacity = capacity;
    }

    public int get(int i){
        if(i<0 || i>= arrayList.size()){
            throw new IllegalArgumentException("Index is out of bounds.");
        }
        return arrayList.get(i);
    }

    public void set(int i, int n){
        if(i<0 || i>= arrayList.size()){
            throw new IllegalArgumentException("Index is out of bounds.");
        }
        arrayList.set(i, n);
    }

    public void pushback(int n){
        if(arrayList.size() == capacity){
            resize();
        }
        arrayList.add(n);
    }

    public int popback(){
        if(arrayList.isEmpty()){
            throw new IllegalStateException("ArrayList is empty");
        }
        int lastIndex = arrayList.size() - 1;
        int poppedElement = arrayList.get(lastIndex);
        arrayList.remove(lastIndex);
        return poppedElement;
    }

    private void resize(){
        capacity *= 2;
        ArrayList<Integer> newArray = new ArrayList<Integer>(capacity);
        newArray.addAll(arrayList);
        arrayList = newArray;
    }

    public int getSize(){
        return arrayList.size();
    }

    public int getCapacity(){
        return capacity;
    }

}