Example usage for java.util Optional of

Introduction

In this page you can find the example usage for java.util Optional of.

Prototype

public static <T> Optional<T> of(T value)

Source Link

Document

Returns an Optional describing the given non- null value.

Usage

From source file:Main.java

/**
 * @return the last element in the list, or empty if the list is empty
 *//*from  w w  w  .  j a  v a  2s . co m*/
public static <E> Optional<E> last(List<E> list) {
    if (list.isEmpty())
        return Optional.empty();
    return Optional.of(list.get(list.size() - 1));
}

From source file:Main.java

static <E> Optional<E> max(List<E> elements, Comparator<E> comparator) {
    //TODO Implement me
    E maxValue = elements.get(0);/*from   w w  w.  j a v a  2s.  com*/
    int i = 0;
    while (i <= elements.size()) {
        maxValue = comparator.compare(maxValue, elements.get(i)) > 0 ? maxValue : elements.get(i);
        i++;
    }
    return Optional.of(maxValue);
}

From source file:Main.java

public static <E> Optional<E> min(List<E> elements, Comparator<E> comparator) {
    if (elements.size() != 0) {
        E minElement = elements.get(0);//from w  w  w .j av  a2 s  . c o m
        for (int i = 1; i < elements.size(); i++) {
            minElement = comparator.compare(minElement, elements.get(i)) < 0 ? minElement : elements.get(i);
        }
        return Optional.of(minElement);
    } else
        return Optional.empty();
}

From source file:Main.java

public static <E> Optional<E> max(List<E> elements, Comparator<E> comparator) {
    if (elements.size() != 0) {
        E maxElement = elements.get(0);//from   w  ww  .ja  v a2  s. c  o m
        for (int i = 1; i < elements.size(); i++) {
            maxElement = comparator.compare(maxElement, elements.get(i)) > 0 ? maxElement : elements.get(i);
        }
        return Optional.of(maxElement);
    } else
        return Optional.empty();
}

From source file:Main.java

public static Optional<String> getTextOfElement(List<XMLEvent> events, String elementName) {
    Optional<Characters> characters = getCharacterEventOfElement(events, elementName);

    if (characters.isPresent())
        return Optional.of(characters.get().getData());

    return Optional.empty();
}

From source file:Main.java

public static Optional<XMLEvent> getStartElement(List<XMLEvent> events, String elementName) {
    Iterator<XMLEvent> iterator = events.iterator();

    while (iterator.hasNext()) {
        XMLEvent event = iterator.next();

        if (event.isStartElement() && event.asStartElement().getName().getLocalPart().equals(elementName))
            return Optional.of(event);

    }/*  ww w . j a v a 2 s  .com*/

    return Optional.empty();
}

From source file:Main.java

@SuppressWarnings("empty-statement")
public static Optional<String> nextTag(XMLStreamReader reader) throws XMLStreamException {
    while (reader.hasNext() && reader.next() != XMLStreamReader.START_ELEMENT)
        ;/*from  ww w . ja  v a2  s  . c  o  m*/
    if (reader.getEventType() == XMLStreamReader.END_DOCUMENT) {
        return Optional.empty();
    } else {
        return Optional.of(reader.getName().getLocalPart());
    }
}

From source file:Main.java

public static Optional<Characters> getCharacterEventOfElement(List<XMLEvent> events, String elementName) {
    Iterator<XMLEvent> iterator = events.iterator();

    while (iterator.hasNext()) {
        XMLEvent event = iterator.next();

        if (event.isStartElement() && event.asStartElement().getName().getLocalPart().equals(elementName)) {
            XMLEvent nextEvent = iterator.next();
            if (nextEvent.isCharacters())
                return Optional.of(nextEvent.asCharacters());
        }//from ww w  .j ava2s .  co m

    }

    return Optional.empty();
}

From source file:Main.java

public static <T> Optional<T> findAnyIn(Collection<T> collection) {
    final Iterator<T> iterator = collection.iterator();
    if (iterator.hasNext()) {
        return Optional.of(iterator.next());
    }//from   w ww  . ja v  a  2 s .co m
    return Optional.empty();
}

From source file:Main.java

/**
 * Returns item in HashSet that matches the specified Predicate.
 * @param set the HashSet to check against
 * @param condition the Predicate to check
 * @param <T> the type of objects in the HashSet
 * @return an Optional containing the matching object, Empty if not found
 * @throws IllegalArgumentException if HashSet or Predicate is null
 *///  w w w .  j  a va 2s .  com
public static <T> Optional<T> getItemInHashSet(final HashSet<T> set, final Predicate<T> condition) {
    if (set == null)
        throw new IllegalArgumentException("HashSet cannot be null!");
    if (condition == null)
        throw new IllegalArgumentException("Predicate cannot be null!");
    for (final T object : set)
        if (condition.test(object))
            return Optional.of(object);
    return Optional.empty();
}