### Question:
ArrayUtil { public static <T> int getNullIndex(final T[] array) { for (int i = 0; i < array.length; i++) { if (array[i] == null) { return i; } } return -1; } private  ArrayUtil(); static int getNullIndex(final T[] array); static boolean containsValue(final T value, final T[] array);  }### Answer:
@Test public void shouldGetCorrectNullIndex() { Double[] doubles1 = new Double[]{10.0, null, null}; Double[] doubles2 = new Double[]{null, null, null}; Double[] doubles3 = new Double[]{10.0, 9.0, 8.0}; assertThat(ArrayUtil.getNullIndex(doubles1), equalTo(1)); assertThat(ArrayUtil.getNullIndex(doubles2), equalTo(0)); assertThat(ArrayUtil.getNullIndex(doubles3), equalTo(-1)); }
@Test public void shouldGetCorrectNullIndex() { final Double[] doubles1 = new Double[]{10.0, null, null}; final Double[] doubles2 = new Double[]{null, null, null}; final Double[] doubles3 = new Double[]{10.0, 9.0, 8.0}; assertThat(ArrayUtil.getNullIndex(doubles1), equalTo(1)); assertThat(ArrayUtil.getNullIndex(doubles2), equalTo(0)); assertThat(ArrayUtil.getNullIndex(doubles3), equalTo(-1)); }