Conflicting overloading of Java – hamcrest matcher

The matcher isiterablecontaininginanyorder has two overloads on the static factory method containsinanyorder (both have the return type matcher < Java. Lang. Iterable >):

> containsInAnyOrder(java.util.Collection< Matcher<？super T>> itemMatchers) > containsInAnyOrder(Matcher<？super T> … itemMatchers)

Now consider the following procedure:

import static org.hamcrest.collection.IsIterableContainingInAnyOrder.containsInAnyOrder;
import static org.hamcrest.core.IsEqual.equalTo;
import static org.junit.Assert.assertThat;

import java.util.Arrays;

import org.junit.Test;

public class SomeTest {

    @SuppressWarnings("unchecked")
    @Test
    public void foo() {
        assertThat(Arrays.asList("foo","bar"),containsInAnyOrder(equalTo("foo"),equalTo("bar")));
    }

}

When it is executed as a JUnit test, it passes as expected It uses the second overload of containsinanyorder shown above

Now, when I change the assertion to this time (exactly matching the example given in the documentation of the first overload):

assertThat(Arrays.asList("foo",containsInAnyOrder(Arrays.asList(equalTo("foo"),equalTo("bar"))));
                              ^^^^^^^^^^^^^^

It no longer compiles because the compiler now infers the return type of containsinanyorder

Matcher<Iterable<? extends List<Matcher<String>>>>

It seems that the compiler still chooses the second overload If it uses the first example, it should be valid Why is it like this? How can I do this?

I use hamcrest 1.3 and Oracle Java 1.7

Solution

It actually matches two overloaded methods I'm not sure why I choose the first one, but you can provide a hint to let it choose the right method

By casting parameters to collection:

assertThat(Arrays.asList("foo",containsInAnyOrder((Collection)Arrays.asList(equalTo("foo"),equalTo("bar"))));

Or specify the generic type T as < string > (but static import cannot be used):

assertThat(Arrays.asList("foo",IsIterableContainingInAnyOrder.<String>containsInAnyOrder(Arrays.asList(equalTo("foo"),equalTo("bar"))));