java collection traversal Set

Traversing a collection of generally set in two ways:  
1. iterating:  

1 Set<String> set = new HashSet<String>();  
2 Iterator<String> it = set.iterator();  
3 while (it.hasNext()) {  
4   String str = it.next();  
5   System.out.println(str);  
6 }

This method uses an iterator, slightly cumbersome, in fact, consider using the second method:
2.For loop through:  

1 for (String str : set) {  
2   System.out.println(str);  
3 } 

Note: You can not make changes while operating at the time of the set assembled in traverse, such as delete, this will cause a crash.

 

If the advantage is also reflected in the generic set is stored in the Object  
  
for loop through:

 1 Set<Object> set = new HashSet<Object>();  
 2 for循环遍历：  
 3 for (Object obj: set) {  
 4       if(obj instanceof Integer){  
 5                 int aa= (Integer)obj;  
 6              }else if(obj instanceof String){  
 7                String aa = (String)obj;
 8              }  
 9               ........  
10 }