set集合迭代，

set集合迭代，

1.迭代遍历

Set<String> set = new HashSet<String>();  
Iterator<String> it = set.iterator();  
while (it.hasNext()) {  
  String str = it.next();  
  System.out.println(str);  
}  

2.for循环遍历：

for (String str : set) {  
      System.out.println(str);  
}  

3.优点还体现在泛型 假如 set中存放的是Object

Set<Object> set = new HashSet<Object>();  
for循环遍历：  
for (Object obj: set) {  
   if(obj instanceof Integer){  
      int aa= (Integer)obj;  
   }else if(obj instanceof String){  
      String aa = (String)obj  
   }  
   ........  
}