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

/**
 * Answer a set containing all elements that are both in source and in query
 * Delete these elements from source Creation date: (13.10.2002 16:23:00)
 * // w  w w.ja  va  2  s.co m
 * @return java.util.Set
 * @param source
 *            java.util.Set
 * @param elements
 *            java.util.Collection
 */
public static Set extractFrom(Set source, Collection query) {
    Set answer = new HashSet();
    Iterator i = query.iterator();
    while (i.hasNext()) {
        Object o = i.next();
        if (source.remove(o)) {
            answer.add(o);
        }
    }
    return answer;
}

From source file:Main.java

/**
 * Returns the number of occurrences of <i>obj</i> in <i>col</i>.
 *///w  ww  .ja va 2 s  .  c  om
public static int cardinality(Object obj, final Collection col) {
    int count = 0;
    Iterator it = col.iterator();
    while (it.hasNext()) {
        Object elt = it.next();
        if ((null == obj && null == elt) || obj.equals(elt)) {
            count++;
        }
    }
    return count;
}

From source file:Main.java

public static <T> T firstElement(final Collection<T> values) {
    if (values != null && values.size() > 0) {
        return values.iterator().next();
    }/*from w w w.java 2 s. c  o m*/
    return null;
}

From source file:Main.java

/** Returns a new array or null if collection is empty */
public static <T> T[] toArray(Collection<T> c) {
    return c.isEmpty() ? null : toArray(c, c.iterator().next().getClass());
}

From source file:MainClass.java

protected static void print(String label, Collection c) {

    System.out.println("--------------" + label + "--------------");

    Iterator it = c.iterator();
    while (it.hasNext()) {
        System.out.println(it.next());
    }//from w ww .  j  av  a  2s. c  o  m
}

From source file:Main.java

public static String getPrettyString(Collection<?> coll) {
    StringBuffer sb = new StringBuffer();
    Iterator<?> it = coll.iterator();

    while (it.hasNext()) {
        String s = it.next().toString();
        sb.append(s + "\n");
    }/*from   w  w  w .ja  v a2  s .c  om*/

    return sb.toString().trim();
}

From source file:Main.java

public static <T> T first(Collection collection) {
    if (size(collection) > 0) {
        return (T) collection.iterator().next();
    }//from   ww  w.  j  a v a 2 s. c o m
    return null;
}

From source file:Main.java

/**
 * Compares two collections returning the number of elements they have in common
 * // w w  w  .  ja v a  2  s .  c o m
 * @param <T>
 * @param one
 * @param two
 * @return
 */
public static <T> int collectionCompare(Collection<T> one, Collection<T> two) {
    int count = 0;

    Iterator<T> e = one.iterator();
    while (e.hasNext()) {
        if (two.contains(e.next()))
            ++count;
    }

    return count;
}

From source file:Main.java

/**
 * Returns a new {@link Collection} containing <tt><i>a</i> - <i>b</i></tt>.
 * The cardinality of each element <i>e</i> in the returned {@link Collection}
 * will be the cardinality of <i>e</i> in <i>a</i> minus the cardinality
 * of <i>e</i> in <i>b</i>, or zero, whichever is greater.
 *
 * @param a  the collection to subtract from, must not be null
 * @param b  the collection to subtract, must not be null
 * @return a new collection with the results
 * @see Collection#removeAll//from w  w  w  . j  a  v  a  2  s .co m
 */
public static Collection subtract(final Collection a, final Collection b) {
    ArrayList list = new ArrayList(a);
    for (Iterator it = b.iterator(); it.hasNext();) {
        list.remove(it.next());
    }
    return list;
}

From source file:Main.java

/**
 * Searches for and returns the first string which starts with the given
 * prefix. Removes the match from the collection.
 *
 * @param collection the collection./*from   ww w.j  ava2  s .  co m*/
 * @param prefix     the string prefix.
 * @return a string, or null if no matches.
 */
public static String popStartsWith(Collection<String> collection, String prefix) {
    Iterator<String> iterator = collection.iterator();

    while (iterator.hasNext()) {
        String element = iterator.next();

        if (element != null && element.startsWith(prefix)) {
            iterator.remove();
            return element;
        }
    }

    return null;
}