### Question:
StringUtils { public static String arrayToString(Object array) { if (array == null) { throw new NullPointerException(); } if (array instanceof int[]) { return Arrays.toString((int[]) array); } if (array instanceof long[]) { return Arrays.toString((long[]) array); } if (array instanceof Object[]) { return Arrays.toString((Object[]) array); } if (array instanceof byte[]) { return Arrays.toString((byte[]) array); } if (array instanceof double[]) { return Arrays.toString((double[]) array); } if (array instanceof float[]) { return Arrays.toString((float[]) array); } if (array instanceof boolean[]) { return Arrays.toString((boolean[]) array); } if (array instanceof char[]) { return Arrays.toString((char[]) array); } if (array instanceof short[]) { return Arrays.toString((short[]) array); } if (array.getClass().isArray()) { return "<unknown array type>"; } else { throw new IllegalArgumentException("The given argument is no array."); } } private  StringUtils(); static String byteToHexString(final byte[] bytes, final int start, final int end); static String byteToHexString(final byte[] bytes); static byte[] hexStringToByte(final String hex); static String arrayAwareToString(Object o); static String arrayToString(Object array); static String showControlCharacters(String str); static String getRandomString(Random rnd, int minLength, int maxLength); static String getRandomString(Random rnd, int minLength, int maxLength, char minValue, char maxValue); static String generateRandomAlphanumericString(Random rnd, int length); static void writeString(@Nonnull String str, DataOutputView out); static String readString(DataInputView in); static void writeNullableString(@Nullable String str, DataOutputView out); static @Nullable String readNullableString(DataInputView in); static boolean isNullOrWhitespaceOnly(String str); @Nullable static String concatenateWithAnd(@Nullable String s1, @Nullable String s2); static String toQuotedListString(Object[] values);  }### Answer:
@Test public void testArrayToString() { double[] array = {1.0}; String controlString = StringUtils.arrayToString(array); assertEquals("[1.0]", controlString); }