public interface Bag extends Collection{ int getCount(Object object); boolean add(Object object); boolean add(Object object, int nCopies); boolean remove(Object object); boolean remove(Object object, int nCopies); Set uniqueSet(); int size(); boolean containsAll(Collection coll); boolean removeAll(Collection coll); boolean retainAll(Collection coll); IteraTor iteraTor();}public interface SortedBag extends Bag{ public ComparaTor comparaTor(); public Object first(); public Object last();}public abstract class DefaultMapBag implements Bag{ private Map _map = null;//底层数据存储区 private int _total = 0; //元素总个数 private int _mods = 0;//修改次数 public DefaultMapBag() { } protected DefaultMapBag(Map map) { setMap(map); } public boolean add(Object object) { return add(object, 1); } public boolean add(Object object, int nCopies) { _mods++; if (nCopies > 0) { int count = (nCopies + getCount(object)); _map.put(object, new Integer(count)); _total += nCopies; return (count == nCopies); } else { return false; } } public boolean addAll(Collection coll) { boolean changed = false; IteraTor i = coll.iteraTor(); while (i.hasNext()) { boolean added = add(i.next()); changed = changed || added; } return changed; } public void clear() { _mods++; _map.clear(); _total = 0; } public boolean contains(Object object) { return _map.containsKey(object); } public boolean containsAll(Collection coll) { return containsAll(new HashBag(coll)); } public boolean containsAll(Bag other) { boolean result = true; IteraTor i = other.uniqueSet().iteraTor(); while (i.hasNext()) { Object current = i.next(); boolean contains = getCount(current) >= other.getCount(current); result = result && contains; } return result; } public boolean equals(Object object) { if (object == this) { return true; } if (object instanceof Bag == false) { return false; } Bag ther = (Bag) object; if (other.size() != size()) { return false; } for (IteraTor it = _map.keySet().iteraTor(); it.hasNext();) { Object element = it.next(); if (other.getCount(element) != getCount(element)) { return false; } } return true; } public int hashCode() { return _map.hashCode(); } public boolean isEmpty() { return _map.isEmpty(); } public IteraTor iteraTor() { return new BagIteraTor(this, extractList().iteraTor()); } static class BagIteraTor implements IteraTor { private DefaultMapBag _parent = null; private IteraTor _support = null;//原始迭代器 private Object _current = null;//当前元素 private int _mods = 0; public BagIteraTor(DefaultMapBag parent, IteraTor support) { _parent = parent; _support = support; _current = null; _mods = parent.modCount(); } public boolean hasNext() { return _support.hasNext(); } public Object next() { if (_parent.modCount() != _mods) { throw new ConcurrentModificationException(); } _current = _support.next(); return _current; } public void remove() { if (_parent.modCount() != _mods) { throw new ConcurrentModificationException(); } _support.remove(); _parent.remove(_current, 1); _mods++; } } public boolean remove(Object object) { return remove(object, getCount(object)); } public boolean remove(Object object, int nCopies) { _mods++; boolean result = false; int count = getCount(object); if (nCopies nCopies) { _map.put(object, new Integer(count - nCopies)); result = true; _total -= nCopies; } else { // count > 0 && count <= i // need to remove all result = (_map.remove(object) != null); _total -= count; } return result; } public boolean removeAll(Collection coll) { boolean result = false; if (coll != null) { IteraTor i = coll.iteraTor(); while (i.hasNext()) { boolean changed = remove(i.next(), 1); result = result || changed; } } return result; } public boolean retainAll(Collection coll) { return retainAll(new HashBag(coll)); } public boolean retainAll(Bag other) { boolean result = false; Bag excess = new HashBag(); IteraTor i = uniqueSet().iteraTor(); while (i.hasNext()) { Object current = i.next(); int myCount = getCount(current); int therCount = other.getCount(current); if (1 <= otherCount && otherCount 0; index--) { result.add(current); } } return result; } private int modCount() { return _mods; } public String toString() { StringBuffer buf = new StringBuffer(); buf.append("["); IteraTor i = uniqueSet().iteraTor(); while (i.hasNext()) { Object current = i.next(); int count = getCount(current); buf.append(count); buf.append(":"); buf.append(current); if (i.hasNext()) { buf.append(","); } } buf.append("]"); return buf.toString(); }}public class HashBag extends DefaultMapBag implements Bag{ public HashBag() { super(new HashMap()); } public HashBag(Collection coll) { this(); addAll(coll); }}public class TreeBag extends DefaultMapBag implements SortedBag{ public TreeBag() { super(new TreeMap()); } public TreeBag(ComparaTor comparaTor) { super(new TreeMap(comparaTor)); } public TreeBag(Collection coll) { this(); addAll(coll); } public Object first() { return ((SortedMap) getMap()).firstKey(); } public Object last() { return ((SortedMap) getMap()).lastKey(); } public ComparaTor comparaTor() { return ((SortedMap) getMap()).comparaTor(); }}
使用decorate模式的Bag工具类
public class BagUtils{ /** * An empty unmodifiable bag. */ public static final Bag EMPTY_BAG = UnmodifiableBag.decorate(new HashBag()); /** * An empty unmodifiable sorted bag. */public static final Bag EMPTY_SORTED_BAG = UnmodifiableSortedBag.decorate(new TreeBag()); public BagUtils() {//这里按常理不应该是public，应该是private才对，作者应该有其他地方要用到吧 } public static Bag synchronizedBag(Bag bag) { return SynchronizedBag.decorate(bag); } public static Bag unmodifiableBag(Bag bag) { return UnmodifiableBag.decorate(bag); } public static Bag predicatedBag(Bag bag, Predicate predicate) { return PredicatedBag.decorate(bag, predicate); } public static Bag typedBag(Bag bag, Class type) { return TypedBag.decorate(bag, type); } public static Bag transformedBag(Bag bag, Transformer transformer) { return TransformedBag.decorate(bag, transformer); } public static SortedBag synchronizedSortedBag(SortedBag bag) { return SynchronizedSortedBag.decorate(bag); } public static SortedBag unmodifiableSortedBag(SortedBag bag) { return UnmodifiableSortedBag.decorate(bag); } public static SortedBag predicatedSortedBag(SortedBag bag, Predicate predicate) { return PredicatedSortedBag.decorate(bag, predicate); } public static SortedBag typedSortedBag(SortedBag bag, Class type) { return TypedSortedBag.decorate(bag, type); } public static SortedBag transformedSortedBag(SortedBag bag, Transformer transformer) { return TransformedSortedBag.decorate(bag, transformer); }}
每个人都有自己鲜明的主张和个性，
