Example usage for java.util Collection iterator

Introduction

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

Prototype

Iterator<E> iterator();

Source Link

Document

Returns an iterator over the elements in this collection.

Usage

From source file:Main.java

/**
 * Joins the elements in an input collection using a given separator.
 *
 * @param <A> Key type//  www . ja  va2 s.  c o  m
 * @param collection Input collection
 * @param separator Separator
 * @return {@code String} representation of the input {@code collection}
 */
public static <A> String join(Collection<A> collection, String separator) {
    if (collection.isEmpty())
        return "";

    Iterator<A> it = collection.iterator();
    StringBuilder out = new StringBuilder();
    out.append(it.next());

    while (it.hasNext())
        out.append(separator).append(it.next());

    return out.toString();
}

From source file:Main.java

public static Object oneOrMany(final Collection<?> collection) {
    switch (size(collection)) {
    case 0:/*www. j a v a 2  s .  c om*/
        return null;
    case 1:
        return collection.iterator().next();
    default:
        return collection;
    }
}

From source file:Main.java

/**
 * Returns true if both collections contain the same elements and the elements are in the same order.
 * Note that the start elements do not have to be the equal!
 * @param s1 The first collection//from   ww  w .ja v  a2  s.  c o  m
 * @param s2 The second collection
 * @return true if s1 and s2 are same in the sense explained above. 
 */
public static boolean sameElementsSameOrder(Collection<?> s1, Collection<?> s2) {
    if (s1.size() != s2.size())
        return false;

    Iterator<?> it1 = s1.iterator();
    Object first = it1.next();
    for (Iterator<?> it2 = s2.iterator(); it2.hasNext();) {
        if (it2.next().equals(first)) {
            while (it1.hasNext()) {
                if (!it2.hasNext())
                    it2 = s2.iterator();
                if (!it1.next().equals(it2.next()))
                    return false;
            }
            return true;
        }
    }
    return false;
}

From source file:Main.java

/**
 * Returns the given Collection as formatted String
 *//*w  w w .j a  va  2  s  .  com*/
public static String toString(Collection<?> c) {
    StringBuilder buffer = new StringBuilder();

    Iterator it = c.iterator();
    for (int i = 0; it.hasNext(); i++) {
        buffer.append(i).append(": ").append(it.next()).append('\n');
    }

    // Delete the last \n
    if (buffer.length() > 1) {
        buffer.setLength(buffer.length() - 1);
    }
    return buffer.toString();
}

From source file:Main.java

public static boolean hasValue(Map<?, ?> map, String key, String val) {
    if (map == null) {
        return false;
    }/*  w  ww.j a  v a2 s.c o m*/
    Collection<?> col = (Collection<?>) map.get(key);
    if (col == null) {
        return false;
    }
    Iterator<?> itr = col.iterator();
    while (itr.hasNext()) {
        String str = (String) itr.next();
        if (str.equalsIgnoreCase(val)) {
            return true;
        }
        if (str.toLowerCase().startsWith(val)) {
            return true;
        }
    }
    return false;
}

From source file:Main.java

public static <E> E getElementAtIndex(Collection<E> set, int idx) {
    if (idx >= set.size() || idx < 0) {
        throw new IndexOutOfBoundsException();
    }/*w w  w.ja  v a  2 s. co  m*/
    Iterator<E> it = set.iterator();
    for (int i = 0; i < idx; ++i) {
        it.next();
    }
    return it.next();
}

From source file:Main.java

@SuppressWarnings("rawtypes")
public static boolean allNotIn(Collection source, Collection target) {
    if (target == null || target.size() == 0) {
        return true;
    }// ww w .  j a va 2 s.  co  m
    for (Iterator it = source.iterator(); it.hasNext();) {
        Object candidate = it.next();
        if (target.contains(candidate)) {
            return false;
        }
    }
    return true;
}

From source file:Main.java

/**
 * Return the last element of a collection. This method iterates over the complete collection to found
 * the last element.//from w w w . j  ava 2 s .  c o  m
 *
 * @param collection The collection to get the last element from.
 * @param <T> The type of value.
 * @return The last element of the collection. If there is no element, the method return null.
 */
public static <T> T last(Collection<T> collection) {
    if (collection.isEmpty()) {
        return null;
    }

    Iterator<T> iterator = collection.iterator();

    for (int i = 0; i < collection.size() - 1; i++) {
        iterator.next();
    }

    return iterator.next();
}

From source file:Main.java

/**
 * Returns a {@link Map} mapping each unique element in the given
 * {@link Collection} to an {@link Integer} representing the number
 * of occurrences of that element in the {@link Collection}.
 * <p>/* w  w w  . j a v a 2  s . c  o m*/
 * Only those elements present in the collection will appear as
 * keys in the map.
 *
 * @param coll  the collection to get the cardinality map for, must not be null
 * @return the populated cardinality map
 */
public static Map getCardinalityMap(final Collection coll) {
    Map count = new HashMap();
    for (Iterator it = coll.iterator(); it.hasNext();) {
        Object obj = it.next();
        Integer c = (Integer) (count.get(obj));
        if (c == null) {
            count.put(obj, INTEGER_ONE);
        } else {
            count.put(obj, new Integer(c.intValue() + 1));
        }
    }
    return count;
}

From source file:Main.java

@SuppressWarnings("unchecked")
public static <T> T[] collectionToArray(Collection<T> sourceCollection, Class<?> elementClass) {
    Object array = Array.newInstance(elementClass, sourceCollection.size());
    Iterator iterator = sourceCollection.iterator();
    for (int i = 0; i < sourceCollection.size(); i++) {
        Array.set(array, i, iterator.next());
    }//from   w w w .  j  av  a  2  s  . c  om
    return (T[]) array;
}