# Converting Primitive int array to list

I am trying to solve the following problem. There are two arrays A of size n and B of size n+1. A and B have all elements same. B has one extra element. Find the element.

My logic is to convert the array to list and check if each element in B is present in A.

But when I am using the primitive arrays my logic is not working. If I am using

```Integer [] a ={1,4,2,3,6,5};
Integer [] b = {2,4,1,3,5,6,7};
```

My code is working fine.

```public static void main(String [] args)
{
int [] a ={1,4,2,3,6,5};
int [] b = {2,4,1,3,5,6,7};
List<Integer> l1 = new ArrayList(Arrays.asList(a));
List<Integer> l2 = new ArrayList(Arrays.asList(b));
for(Integer i :l2)
{
if(!l1.contains(i))
{
System.out.println(i);
}
}
}
```

And also My logic is O(n+1). Is there any better algo.

Thanks

## Answer

The reason it is not working for primitive arrays, is that Arrays.asList when given an int[ ] returns a List<Integer[ ]> rather than a List<Integer>.

Guava has an answer to this in the Ints class. Is has an asList method that will take an int[ ] and return a List<Integer>

Update

```int[] a = ...;
int[] b = ...;
List<Integer> aList = Ints.asList(a);
List<Integer> bList = Ints.asList(b);
```

The above will allow your code to work properly for int[ ] as it works for Integer[ ].

Check out Ints API