这是我的课：
public class MultiSet<E> extends AbstractCollection<E>
{
private int size = 0;
private Map<E, Integer> values = new HashMap<E, Integer>();
public MultiSet()
{
}
public MultiSet(Collection<E> c)
{
addAll(c);
}
@Override
public boolean add(E o)
{
throw new UnsupportedOperationException();
}
@Override
public boolean remove(Object o)
{
throw new UnsupportedOperationException();
}
public Iterator<E> iterator()
{
return new Iterator<E>()
{
private Iterator<E> iterator = values.keySet().iterator();
private int remaining = 0;
private E current = null;
public boolean hasNext()
{
return remaining > 0 || iterator.hasNext();
}
public E next()
{
if (remaining == 0)
{
remaining = values.get(current);
}
remaining--;
return current;
}
public void remove()
{
throw new UnsupportedOperationException();
}
};
}
public boolean equals(Object object)
{
if (this == object) return true;
if (this == null) return false;
if (this.getClass() != object.getClass()) return false;
MultiSet<E> o = (MultiSet<E>) object;
return o.values.equals(values);
}
public int hashCode()
{
return values.hashCode()*163 + new Integer(size).hashCode()*389;
}
public String toString()
{
String res = "";
for (E e : values.keySet());
//res = ???;
return getClass().getName() + res;
}
public int size()
{
return size;
}
}
所以基本上，我需要正确实现我的添加/删除方法，向/从Set.
对我来说，我的观点似乎equals是正确的，但 Eclipse 在一行中说：
MultiSet<E> o = (MultiSet<E>) object;
有unchecked cast from object to Multiset<E>
什么想法吗？
另外，在我的toString方法中，我不是 100% 确定如何定义“res”？
谢谢，//克里斯