java遍历set集合

1.迭代遍历： 
import java.util.*;


Set<String> keys = new HashSet<String>();  
Iterator<String> it = keys.iterator();  
for(Iterator it=keys.iterator(); it.hasNext();) {  
  String str = (String)it.next();  
  System.out.println(str);  
}  
  
2.for循环遍历：  
for (String str : keys) {  
      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  
  }  
  ........  
}