Example usage for java.util Collections emptyList

Introduction

In this page you can find the example usage for java.util Collections emptyList.

Prototype

@SuppressWarnings("unchecked")
public static final <T> List<T> emptyList()

Source Link

Document

Returns an empty list (immutable).

Usage

From source file:Main.java

public static List<String> split(String str, char delimiter) {

    if (TextUtils.isEmpty(str)) {
        return Collections.emptyList();
    }/*from ww  w  . java 2s.com*/

    int substringsCount = 1;
    for (int i = 0, len = str.length(); i < len; i++) {
        if (str.charAt(i) == delimiter) {
            substringsCount++;
        }
    }

    if (substringsCount == 1) {
        return Collections.singletonList(str);
    }

    List<String> split = new ArrayList<String>(substringsCount);

    int index = str.indexOf(delimiter);
    int lastIndex = 0;
    while (index != -1) {

        split.add(str.substring(lastIndex, index));

        lastIndex = index + 1;
        index = str.indexOf(delimiter, lastIndex);
    }

    split.add(str.substring(lastIndex, str.length())); // add the final string after the last delimiter

    return split;
}

From source file:Main.java

/**
 * //from   ww  w.j  ava  2s . c om
 * @param elements
 * @return
 */
public static <E> List<E> asList(E... elements) {
    if (elements == null || elements.length == 0) {
        return Collections.emptyList();
    }
    // Avoid integer overflow when a large array is passed in
    int capacity = computeListCapacity(elements.length);
    ArrayList<E> list = new ArrayList<E>(capacity);
    Collections.addAll(list, elements);
    return list;
}

From source file:Main.java

public static <X, Y> List<Y> mapWithFoldr(List<X> xs, Function<X, Y> mapper) {
    return foldr(xs, Collections.emptyList(), x -> res -> cons(mapper.apply(x), res));
}

From source file:Main.java

public static <T> Collection<Collection<T>> split(Iterable<T> coll, int size) {
    if (size < 1) {
        return Collections.emptyList();
    }/*from w w w  .j  ava 2  s  .co m*/
    final List<Collection<T>> ret = new ArrayList<>();
    final Iterator<T> it = coll.iterator();
    Collection<T> box = null;
    for (int i = 0; it.hasNext(); ++i) {
        if (i % size == 0) {
            if (box != null) {
                ret.add(box);
            }
            box = new ArrayList<>(size);
        }
        //noinspection ConstantConditions
        box.add(it.next());
    }
    if (box != null) {
        ret.add(box);
    }
    return ret;
}

From source file:Main.java

public static List<?> toList(Object obj) {
    if (obj instanceof List) {
        return (List<?>) obj;
    } else if (obj == null) {
        return Collections.emptyList();
    } else {/*from  w  w w  .  ja  v  a2s  .  c o m*/
        return Arrays.asList(obj);
    }
}

From source file:Main.java

public static <T, Tout> List<Tout> select(Iterable<T> source, Function<T, Tout> action) {
    if (source == null || !source.iterator().hasNext())
        return Collections.emptyList();
    List<Tout> result = new ArrayList<Tout>();
    for (T item : source) {
        result.add(action.apply(item));/*from w w w  .  j a  v  a 2s  .co  m*/
    }

    return result;

}

From source file:Main.java

/**
 * Like Collections.unmodifiableList(), but with checks for null values.
 *///from  w  ww .jav a 2 s. co  m
public static <T> List<T> unmodifiableList(List<T> list) {

    if (list == null) {
        return Collections.emptyList();
    }

    return Collections.unmodifiableList(list);
}

From source file:Main.java

public static <V> List<V> uniteCollections(Collection<? extends Collection<V>> values) {
    if (isEmpty(values)) {
        return Collections.emptyList();
    }//from ww w .j  a va2  s .  co  m
    List<V> copy = new ArrayList<V>();
    for (Collection<V> collection : values) {
        copy.addAll(collection);
    }
    return copy;
}

From source file:Main.java

public static Collection<String> addElementBeforeAndAfter(Collection<?> collection, String toAddBefore,
        String toAddAfter) {//from   www.  ja  va 2 s .  co  m
    if (collection == null || collection.isEmpty()) {
        return Collections.emptyList();
    }

    List<String> result = new ArrayList<>(collection.size());
    for (Object o : collection) {
        StringBuilder stringBuilder = new StringBuilder(
                o.toString().length() + toAddBefore.length() + toAddAfter.length());
        stringBuilder.append(toAddBefore);
        stringBuilder.append(o.toString().trim());
        stringBuilder.append(toAddAfter);
        result.add(stringBuilder.toString());
    }
    return result;
}

From source file:Main.java

public static List<String> split(String input, String delimiter) {
    if (input == null || input.isEmpty()) {
        return Collections.emptyList();
    }/*from  ww  w  .  j a v a2 s  . co m*/
    return new ArrayList<String>(Arrays.asList(input.split(delimiter)));
}