I'm trying to write a function which returns the difference between two arrays. The input arrays are not sorted. I'm assuming that that all elements in input arrays are unique. For Example:
Input: arr1 = [1,2,3,5,4]
arr2 = [1,2,3]
Expected Output: [4,5]
I'm trying to implement this using an arraylist but can't find the problem with my code. Here it is:
public class Difference{
ArrayList<Integer> diff(int m[],int n[])
{
int mlen = m.length;
int nlen = n.length;
ArrayList<Integer> arr1 = new ArrayList<Integer>(Arrays.asList(m));
ArrayList<Integer> arr2 = new ArrayList<Integer>(Arrays.asList(n));
if(mlen>nlen)
{
arr1.removeAll(arr2);
return arr1;
}
else
{
arr2.removeAll(arr1);
return arr2;
}
}
public static void main(String args[])
{
Difference obj = new Difference();
int a[] = {1,2,3,4,5};
int b[] = {1,2,3};
System.out.println(obj.diff(a,b));
}
}
The issue with your code is that you are trying to use a non-existing constructor for ArrayList(int[] numbers) You either have to add every number from m and n to the ArrayList or use a double brace initialization e.g.
ArrayList < Integer > arr1 = new ArrayList < Integer > () {
{
for (int i: m) add(i);
}
}
ArrayList < Integer > arr2 = new ArrayList < Integer > () {
{
for (int i: n) add(i);
}
}
In one line it would look like this without formatting
new ArrayList<Integer>() {{for(int i:m) add(i);}};
The other preferred way would be to add every number while iterating e.g.
ArrayList<Integer> arr1 = new ArrayList<Integer>();
for(int i: m) arr1.add(i);