自定义Java迭代器类型混乱

问题描述

我有一个绑定对象和命令的泛型类：

  
 
 
 初始化中 Iterator  for（Iterator< OrderedObject< T>> it = s.iterator（）; it.hasNext（）;）{
  
我忽略了什么？
解决方案
混乱是因为内部类 OrderedObjectSetIterator 引入了一个与外部类相同的泛型（ T ）。 Eclipse IDE显示一个警告： 
 
 
 类型参数T隐藏类型T 
 所以我猜你不需要引入另一个参数类型，只是使用与外部类相同的定义。
 
  $ b 
基本上，内部类将被定义为： 
 
 
  private class OrderedObjectSetIterator实现Iterator< T> {
 .... 
  
和迭代器方法一样：
  public Iterator< T> iterator（）{
 return new OrderedObjectSetIterator（）; 
} 
  
 
I have a generic class which bundles an Object and an order:
public class OrderedObject<T> {
    private int order;
    private T object;

    public OrderedObject(int order, T object) {
        this.order = order;
        this.object = object;
    }

    public int getOrder() {
        return order;
    }

    public T getObject() {
        return object;
    }
}
I developed a Set implementation which stores OrderedObject<T> instances and wants to produce an Iterator<T> enumerating in the order enforced by the built-in order:
public class OrderedObjectSet<T> extends AbstractSet<T> implements Set<T> {
    Set<OrderedObject<T>> s = new HashSet<OrderedObject<T>>();

    public boolean add(int order, T object) {
        return s.add(new OrderedObject<T>(order, object));
    }

    public Iterator<T> iterator() {
        return new OrderedObjectSetIterator<T>();
    }

    public int size() {
        return s.size();
    }

    private class OrderedObjectSetIterator<T> implements Iterator<T> {
        private int index;

        public boolean hasNext() {
            return index < s.size();
        }

        public T next() {
            T object = null;

            for (Iterator<OrderedObject<T>> it = s.iterator(); it.hasNext(); ) {
                OrderedObject<T> o = it.next();
                if (o.getOrder() == index) {
                    object = o.getObject();
                }
            }

            index++;
            return object;
        }

        public void remove() {
            throw new UnsupportedOperationException();
        }
    }
}
The latter class does not compile because there seems to some confusion of types in the Iterator initialization at
for (Iterator<OrderedObject<T>> it = s.iterator(); it.hasNext(); ) {
What do I overlook?
 解决方案 
The confusion is because the inner class OrderedObjectSetIterator introduces a generic type called the same (T) as the outer class. Eclipse IDE shows a warning:
The type parameter T is hiding the type T
So I guess you don't need to introduce another parameter type, just use the same as the outer class defines.
Basically, the inner class would be defined as:
private class OrderedObjectSetIterator implements Iterator<T> {
....
And the iterator method as:
public Iterator<T> iterator() {
    return new OrderedObjectSetIterator();
}
                        
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