Example usage for java.util Collection size

Introduction

In this page you can find the example usage for java.util Collection size.

Prototype

int size();

Source Link

Document

Returns the number of elements in this collection.

Usage

From source file:Main.java

@SuppressWarnings("unchecked")
public static <T> T[] toArray(Collection<T> c, Class<T> clazz) {
    if (c == null || c.size() == 0) {
        T[] a = (T[]) java.lang.reflect.Array.newInstance(clazz, 0);
        return Collections.<T>emptyList().toArray(a);
    } else {//  w  w w  .jav  a 2s.c  om
        T[] a = (T[]) java.lang.reflect.Array.newInstance(clazz, c.size());
        return c.toArray(a);
    }
}

From source file:Main.java

/**
 * makes sense only if iteration order deterministic!
 *///from w ww.j  a v a  2s .  co  m
private static <T> T getElement(final boolean remove, final int index, final Collection<T> coll) {
    if (index >= coll.size())
        throw new IndexOutOfBoundsException(index + " >= " + coll.size());

    final Iterator<T> it = coll.iterator();
    int i = 0;

    while (i++ < index)
        it.next();

    final T elem = it.next();
    if (remove)
        it.remove();
    return elem;
}

From source file:Main.java

public static int[] toIntArray(Collection<Integer> integerCollection) {
    int[] intArray = new int[integerCollection.size()];
    int index = 0;

    for (int num : integerCollection) {
        intArray[index] = num;/*  w  w w.j av a 2s .c  o m*/
        index++;
    }

    return intArray;
}

From source file:Main.java

public static boolean isNotEmpty(Collection<?> objs) {
    return objs != null && objs.size() > 0;
}

From source file:Main.java

public static boolean isEmpty(Collection<?> objs) {
    return objs == null || objs.size() == 0;
}

From source file:Main.java

/**
 * Copies a collection into an array./*from w  ww .  j a  v  a  2s  . co m*/
 * 
 * @param collection
 *        is the collection that should be copied to an array
 * @param type
 *        is the class of the elements in the collection
 * @return the array copy
 */
public static <T> T[] toArray(final Collection<T> collection, final Class<T> type) {

    final int size = collection.size();
    @SuppressWarnings("unchecked")
    final T[] array = (T[]) Array.newInstance(type, size);
    collection.toArray(array);

    return array;
}

From source file:Main.java

@SuppressWarnings("unchecked")
public static <E> E[] asArray(final Collection<? extends E> collection) {
    return collection.toArray((E[]) new Object[collection.size()]);
}

From source file:Main.java

public static <K, V> Map<K, V> convertMap(final Map<K, V> map, final Collection<K> keys,
        final Collection<V> values) {
    if (keys.size() != values.size()) {
        throw new IllegalArgumentException("Invalid Collection. Collection size is not equals.");
    }/*w ww  . j  a v a  2s  .c o  m*/
    Iterator<V> valueIt = values.iterator();
    for (K key : keys) {
        map.put(key, valueIt.next());
    }
    return map;
}

From source file:Main.java

public static <T> boolean addAll(Collection<T> collection, Collection<? extends T> toAdd) {
    int size = toAdd.size();
    boolean result = false;
    if (size > 0) {
        if (size < 10)
            for (T element : toAdd)
                result |= collection.add(element);
        else//www  .  ja v  a  2  s. c  o m
            result = collection.addAll(toAdd);
    }
    return result;
}

From source file:Main.java

public static <T> boolean isNull(Collection<T> collection) {
    boolean isNull = true;
    if (collection != null && collection.size() != 0) {
        isNull = false;/*from  ww w  .ja va 2 s  .c o m*/
    }
    return isNull;
}