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

public static Collection and(Collection collection1, Collection collection2) {
    Vector completeList = new Vector();

    if (collection2 == null)
        return completeList;
    Iterator i = collection2.iterator();
    while (i.hasNext()) {
        Object addlItem = i.next();
        if (collection1.contains(addlItem) == true) {
            completeList.addElement(addlItem);
        }//from  w  w w.  j a  v  a2 s .c  o  m
    }
    return completeList;
}

From source file:Main.java

/**
 * Get the first element of the passed collection.
 *
 * @param <ELEMENTTYPE>//  w w w.j a  v  a 2 s . c  om
 *        Collection element type
 * @param aCollection
 *        The collection. May be <code>null</code>.
 * @return <code>null</code> if the collection is <code>null</code> or empty,
 *         the first element otherwise.
 */
@Nullable
public static <ELEMENTTYPE> ELEMENTTYPE getFirstElement(@Nullable final Collection<ELEMENTTYPE> aCollection) {
    return isEmpty(aCollection) ? null : aCollection.iterator().next();
}

From source file:Main.java

@SuppressWarnings("rawtypes")
public static boolean allIn(Collection source, Collection target) {
    if (target == null || target.size() == 0) {
        return false;
    }/* w w  w  .ja  v a 2 s .  co  m*/

    for (Iterator it = source.iterator(); it.hasNext();) {
        Object object = it.next();
        if (!target.contains(object)) {
            return false;
        }
    }
    return true;
}

From source file:Main.java

/**
 * Find a value of the given type in the given collection.
 * @param coll the collection to search/*from  w  w w .j  a va  2 s  . c  om*/
 * @param type the type to look for
 * @return a value of the given type found, or <code>null</code> if none
 * @throws IllegalArgumentException if more than one value
 * of the given type found
 */
public static Object findValueOfType(Collection<?> coll, Class<?> type) throws IllegalArgumentException {
    Object value = null;
    for (Iterator<?> it = coll.iterator(); it.hasNext();) {
        Object obj = it.next();
        if (type.isInstance(obj)) {
            if (value != null) {
                throw new IllegalArgumentException(
                        "More than one value of type [" + type.getName() + "] found");
            }
            value = obj;
        }
    }
    return value;
}

From source file:Main.java

public static String collectionToString(Collection c) {
    StringBuffer buff = new StringBuffer();
    int i = 0;/*  w w w .j  a  va2 s .  c  o  m*/
    int size = c.size();
    for (Iterator iter = c.iterator(); iter.hasNext();) {
        Object object = iter.next();
        if (size > 1 && i == (size - 1)) {
            buff.append("and ");
        }
        buff.append(object);
        if (i < (size - 1)) {
            if (size > 2) {
                buff.append(", ");
            } else {
                buff.append(" ");
            }
        }
        i++;
    }
    return buff.toString();

}

From source file:Main.java

@SuppressWarnings("unchecked")
public static <S, D extends S> D[] downcastToArray(Collection<S> source, Class<D> destClass) {
    D[] dest = (D[]) Array.newInstance(destClass, source.size());
    Iterator<S> it = source.iterator();
    for (int i = 0; i < dest.length; i++) {
        S s = it.next();//from   w w  w.j  a va 2 s . com
        if (destClass.isAssignableFrom(s.getClass()))
            dest[i] = (D) s;
        else
            throw new IllegalArgumentException("Could not downcast element from class "
                    + s.getClass().getSimpleName() + " to " + destClass.getSimpleName());
    }
    return dest;
}

From source file:Main.java

public static Collection<Object> filterCollection(Collection<Object> src, Collection<Object> dest) {

    if (isEmpty(dest))
        return src;
    Iterator<Object> iterator = src.iterator();
    while (iterator.hasNext()) {

        Object next = iterator.next();
        if (dest.contains(next)) {

            iterator.remove();/*from w w w  . j  a  va2s .c o  m*/
        }
    }

    return src;
}

From source file:com.jdy.ddj.common.utils.Collections3.java

public static <T> List<T> subtract(final Collection<T> a, final Collection<T> b) {
    ArrayList<T> list = new ArrayList<T>(a);
    for (Iterator it = b.iterator(); it.hasNext();) {
        list.remove(it.next());/*from ww w .ja  v a 2 s  . c  o  m*/
    }
    return list;
}

From source file:Main.java

/**
 * Returns the first element of the given collection
 * /*from   w  w  w . ja  v a  2s . c  om*/
 * @param <T>
 * @param collection
 * @return <code>null</code> if the first element is <code>null</code> or
 *         the collection is <code>null</code> or empty
 */
public static <T> T firstElementOf(final Collection<? extends T> collection) {
    if (isEmpty(collection)) {
        return null;
    }
    return collection.iterator().next();
}

From source file:Main.java

public static <T> T only(Collection<T> coll) {
    if (coll.size() != 1) {
        throw new NoSuchElementException("Collection has none or more than one elements");
    }//from w w w.  j a  v  a 2  s  .  co m
    return coll.iterator().next();
}