Merge Two Sorted Lists II

Given two sorted integer arrays A and B, merge B into A as one sorted array.

Note: You have to modify the array A to contain the merge of A and B. Do not output anything in your code. TIP: C users, please malloc the result into a new array and return the result.

If the number of elements initialized in A and B are m and n respectively, the resulting size of array A after your code is executed should be m + n

Example :

Input : 
         A : [1 5 8]
         B : [6 9]

Modified A : [1 5 6 8 9]

public class Solution {
    public void merge(ArrayList<Integer> a, ArrayList<Integer> b) {
        int i = 0;
        int j = 0;
        while (j < b.size()) {
            if (i >= a.size() || b.get(j) < a.get(i)) {
                if (i < a.size())
                    a.add(i, b.get(j));
                else
                    a.add(b.get(j));
                j++;
            }
            i++;
        }
    }
}