Why the next method doesn't change the array but the other one changed its values?

Question

the first method doesn't change the array, but the second method changes or swaps the given indexes of the array , why? :

    public class Main{
   public static void changeArr1 (int [] arr) { //doesn't do anything?
 int [] tmp = {10, 20}; 
 arr = tmp; 
}
public static void swap(int[] arr,int i,int j){ //swapping 2 array elements?
int temp = arr[i];
arr[i] = arr[j]
arr[j] = temp;
}
}