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 <T> List<T> toList(Iterable<T> iterable) {
    if (null == iterable)
        return Collections.emptyList();
    List<T> retList = new LinkedList<>();
    for (T item : iterable) {
        retList.add(item);//from  w  w w  .  ja v  a 2 s  .  com
    }
    return retList;
}

From source file:Main.java

/**
 * Sub the list without exception//w  w  w .jav  a2  s  .  c  o  m
 */
public static <T> List<T> safeSubList(List<T> list, int start, int end) {
    if (start >= list.size()) {
        return Collections.emptyList();
    }
    return list.subList(start, Math.min(end, list.size()));
}

From source file:Main.java

public static <K, V> List<V> getValueList(Map<K, List<V>> map, K key) {
    List<V> valueList = map.get(key);
    if (valueList == null) {
        return Collections.emptyList();
    }/* www  . j  a v a2  s. c  om*/
    return valueList;
}

From source file:Main.java

public static <E> List<E> copyNullSafeList(Collection<? extends E> list) {
    if (list.isEmpty()) {
        return Collections.emptyList();
    }/*from w  ww .  j  a  v  a  2  s . co  m*/
    return Collections.unmodifiableList(copyNullSafeMutableList(list));
}

From source file:Main.java

public static final <T> List<List<T>> devide(List<T> origin, int size) {
    if (origin == null || origin.isEmpty() || size <= 0) {
        return Collections.emptyList();
    }/*w  w  w .ja  va  2s  . c om*/

    final int block = origin.size() / size + (origin.size() % size > 0 ? 1 : 0);

    List<List<T>> devidedList = new ArrayList<List<T>>(block);
    for (int i = 0; i < block; i++) {
        final int start = i * size;
        final int end = Math.min(start + size, origin.size());
        devidedList.add(new ArrayList<T>(origin.subList(start, end)));
    }
    return devidedList;
}

From source file:Main.java

@SuppressWarnings("unchecked")
public static <V, T extends Collection<V>> Collection<V> orEmpty(T collection) {
    return (collection == null ? (Collection<V>) Collections.emptyList() : collection);
}

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 www .j a va2  s  .  c  o  m*/
        return Collections.singletonList(obj);
    }
}

From source file:Main.java

public static <T> List<T> safeSubList(List<T> list, int fromIndex, int toIndex) {
    int size = list.size();
    if (fromIndex >= size || toIndex <= 0 || fromIndex >= toIndex) {
        return Collections.emptyList();
    }/* ww  w  . j a  va  2s  . c  o  m*/

    fromIndex = Math.max(0, fromIndex);
    toIndex = Math.min(size, toIndex);

    return list.subList(fromIndex, toIndex);
}

From source file:Main.java

public static <T, C extends Collection<T>> List<T> merge(Collection<C> splits) {
    if (splits == null || splits.isEmpty()) {
        return Collections.emptyList();
    }//from   w  w w .j  a va2 s  . co  m
    List<T> list = new ArrayList<>();
    for (Collection<T> split : splits) {
        list.addAll(split);
    }
    return list;
}

From source file:Main.java

public static <E> List<E> concatList(List<E>... array) {
    if (array == null || array.length < 1) {
        return Collections.emptyList();
    }/*from  w w  w  .j ava  2 s .  c o  m*/
    List<E> newList = new ArrayList<E>();
    for (List<E> e : array) {
        if (isNotEmpty(e)) {
            newList.addAll(e);
        }
    }
    return newList;
}