Why doesn't this code attempting to use Hamcrest's hasItems compile?

Question

Why does this not compile, oh, what to do?

import static org.junit.Assert.assertThat;
import static org.junit.matchers.JUnitMatchers.hasItems;

ArrayList<         


        

Answer 1

ArrayList expected = new ArrayList();
expected.add(1);
expected.add(2);
hasItems(expected);

hasItems(T..t) is being expanded by the compiler to:

hasItems(new ArrayList[]{expected});

You are passing a single element array containing an ArrayList. If you change the ArrayList to an Array, then your code will work.

Integer[] expected = new Integer[]{1, 2};
hasItems(expected);

This will be expanded to:

hasItems(1, 2);