TreeMap get获取数据为null

之前用treeMap进行排序，然后for循环keySet,get(Key)获取到的值是null，后来找到一下方法测了一下，只有没有注释的那个方法是可以获取到值得

public class Test
{

/**
* @param args
*/
public static void main(String[] args)
{
Map<Special, List<Integer>> items = new TreeMap<Special, List<Integer>>((Comparator<? super Special>) new Comparator<Special>()
{
public int compare(Special special1, Special special2)
{
return special2.getIndexNo() < special1.getIndexNo() ? 1 : -1;
}
});
Special a = new SpecialImpl();
a.setId(1);
a.setIndexNo(0);
List<Integer> b = new ArrayList<Integer>();
b.add(1);
b.add(2);
b.add(3);
items.put(a, b);

a = new SpecialImpl();
a.setId(2);
a.setIndexNo(1);
b = new ArrayList<Integer>();
b.add(4);
b.add(5);
b.add(6);
items.put(a, b);

// Set<Special> keySet = items.keySet(); // keySet获取key
// for (Iterator<Special> it = keySet.iterator(); it.hasNext();)
// {
// Special special = it.next();
// System.out.println(special.getId() + "--" + special.getIndexNo() + ":");
// System.out.println(items.get(special));
// }
// 第二种
Set<Map.Entry<Special, List<Integer>>> entrySet = items.entrySet(); // entrySet获取映射关系
Iterator<Map.Entry<Special, List<Integer>>> iter = entrySet.iterator();
while (iter.hasNext())
{
Map.Entry<Special, List<Integer>> me = iter.next();// Map.Entry是entrySet集合的元素类型.
Special special = me.getKey();
List<Integer> c = me.getValue();
System.out.println(special.getId() + "--" + special.getIndexNo() + ":");
System.out.println(c);
}
}

}