List

An ordered collection. Lists can contain duplicate elements.Lists typically allow multiple null elements if they allow null elements at all.

ArrayList

public class ArrayListTest {
    private List<String> list;

    @Before
    public void setUp() throws Exception {
        list = new ArrayList<>();
    }

    @After
    public void tearDown() throws Exception {
        list.clear();
    }

    @Ignore
    @Test
    public void itHasOrderedElements() throws Exception {
        // arrange
        String[] result = new String[3];

        // act
        list.add("1");
        list.add("2");
        list.add("3");

        // assert
        int index = 0;
        Iterator<String> iterator = list.iterator();
        do {
            result[index] = iterator.next();
            index++;
        } while (iterator.hasNext());
        assertThat("it order elements to 123", result, arrayContaining("1", "2", "3"));
    }

    @Ignore
    @Test
    public void itNotSortElementsByDefault() throws Exception {
        // act
        list.add("B");
        list.add("A");
        list.add("C");

        // assert
        String result = "";
        for (String element: list) {
            result += element;
        }
        assertThat("it not sort elements from BAC to ABC or CBA", result, is(not(oneOf("ABC", "CBA"))));
    }

    @Test
    public void itCanHaveDuplicateElement() throws Exception {
        // act
        list.add("fake");
        list.add("fake");

        // assert
        assertThat("it should have 2 elements", list.size(), is(2));
        assertThat("its first element is same as second", list.get(0), is(list.get(1)));
        assertThat("its first element is same instance as second", list.get(0), sameInstance(list.get(1)));
    }

    @Test
    public void itCanHaveNullElement() throws Exception {
        // act
        list.add(null);

        // assert
        assertThat("it should have 1 elements", list.size(), is(1));
        assertThat("it has null element", list.get(0), is(nullValue()));
    }
}

LinkedList

public class LinkedListTest {
    private LinkedList<String> list;

    @Before
    public void setUp() throws Exception {
        list = new LinkedList<>();
    }

    @After
    public void tearDown() throws Exception {
        list.clear();
    }

    @Ignore
    @Test
    public void itHasOrderedElements() throws Exception {
        // arrange
        String[] result = new String[3];

        // act
        list.add("1");
        list.add("2");
        list.add("3");

        // assert
        int index = 0;
        Iterator<String> iterator = list.iterator();
        do {
            result[index] = iterator.next();
            index++;
        } while (iterator.hasNext());
        assertThat("it order elements to 123", result, arrayContaining("1", "2", "3"));
    }

    @Ignore
    @Test
    public void itNotSortElementsByDefault() throws Exception {
        // act
        list.add("B");
        list.add("A");
        list.add("C");

        // assert
        String result = "";
        for (String element: list) {
            result += element;
        }
        assertThat("it not sort elements from BAC to ABC or CBA", result, is(not(oneOf("ABC", "CBA"))));
    }

    @Test
    public void itCanHaveDuplicateElement() throws Exception {
        // act
        list.add("fake");
        list.add("fake");

        // assert
        assertThat("it should have 2 elements", list.size(), is(2));
        assertThat("its first element is same as second", list.get(0), is(list.get(1)));
        assertThat("its first element is same instance as second", list.get(0), sameInstance(list.get(1)));
    }

    @Test
    public void itCanHaveNullElement() throws Exception {
        // act
        list.add(null);

        // assert
        assertThat("it should have 1 elements", list.size(), is(1));
        assertThat("it has null element", list.get(0), is(nullValue()));
    }
}

$ java LinkedListTest
Does LinkedList have ordered elements? true
Does LinkedList sort elements by default? false
Can LinkedList has duplicate elements? true
Can LinkedList has Null element? true