### Question:
ClassUtil { private static <J> Constructor<J> findConstructor(final Class<J> clazz) { return findConstructor(clazz, EMPTY_CLAZZ_ARRAY); } private  ClassUtil(); static Object newInstance(final String javaClassName); static J newInstance(final String javaClassName, final Class<J> type); static J newInstance(final Class<J> clazz); static J newInstance(final Constructor<J> constructor, final Object[] args); static Constructor<J> findConstructor(final Class<J> clazz, final Class<?>[] parameterTypes); static Class<?> classForName(final String javaClassName); static Class<? extends J> classForName(final String javaClassName, final Class<J> type); static Object invoke(final Object instance, final Method method, final Object... args); static void set(final Object instance, final Field field, final Object value); static Object get(final Object instance, final Field field); static Method findMethod(final Class<?> clazz, final String methodName, final Class<?>... parameterTypes); static Collection<Field> getAllFields(final Class<?> clazz, final Class<? extends Annotation> annotation); static Collection<Method> getAllMethods(final Class<?> clazz, final Class<? extends Annotation> annotation); static Collection<Field> getAllFields(final Class<?> clazz); static Collection<Method> getAllMethods(final Class<?> clazz); static Set<Class<?>> getAllInterfaces(final Class<?> clazz); static Class<?> getGeneric(final Constructor<?> constructor, final int i); static Class<?> getGeneric(final Method method, final int i); static Class<?> getGeneric(final Field field); static Class<?> getGeneric(
			final Type type,
			final Supplier<RuntimeException> exceptionSupplier); static String getPropertyName(final Method method);  }### Answer:
@Test public void testGetConstructorException() { assertThrows(Exception.class, () -> { final Constructor<?> constructor = ClassUtil.findConstructor(SD.class, new Class[] { Long.class }); nop(constructor); }); assertThrows(Exception.class, () -> { final Constructor<?> constructor = ClassUtil.findConstructor(ClassUtil.class, new Class[] {}); nop(constructor); }); }
@Test public void testFindConstructor() { final Constructor<StringBuilder> constructor = ClassUtil.findConstructor(StringBuilder.class, new Class[] { String.class }); assertEquals(constructor.getDeclaringClass(), StringBuilder.class); }
@Test public void testFindConstructorWithError() { assertThrows(Exception.class, () -> { final Constructor<StringBuilder> constructor = ClassUtil.findConstructor(StringBuilder.class, new Class[] { Date.class }); nop(constructor); }); }