/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}
 

/**
 * Returns a comparator that compares {@link Comparable} objects in natural
 * order.
 *
 * <p>The returned comparator is serializable and throws {@link
 * NullPointerException} when comparing {@code null}.
 *
 * @param  <T> the {@link Comparable} type of element to be compared
 * @return a comparator that imposes the <i>natural ordering</i> on {@code
 *         Comparable} objects.
 * @see Comparable
 * @since 1.8
 */
@SuppressWarnings("unchecked")
public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
    return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * less than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be less than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(true, comparator);
}
 

/**
 * Returns a null-friendly comparator that considers {@code null} to be
 * greater than non-null. When both are {@code null}, they are considered
 * equal. If both are non-null, the specified {@code Comparator} is used
 * to determine the order. If the specified comparator is {@code null},
 * then the returned comparator considers all non-null values to be equal.
 *
 * <p>The returned comparator is serializable if the specified comparator
 * is serializable.
 *
 * @param  <T> the type of the elements to be compared
 * @param  comparator a {@code Comparator} for comparing non-null values
 * @return a comparator that considers {@code null} to be greater than
 *         non-null, and compares non-null objects with the supplied
 *         {@code Comparator}.
 * @since 1.8
 */
public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
    return new Comparators.NullComparator<>(false, comparator);
}