JAVA集合类

package test;  
import java.util.*;  
import java.util.Map.Entry;  
public class B {    
    public static void main(String[] args) {     
        Map<Integer,Integer> mm = new HashMap<Integer,Integer>();     
        for(int i=0;i<10;i++)   {  
            mm.put(i, i);   
        }     
        for( Entry<Integer, Integer> e : mm.entrySet()) {  
            System.out.println("key:"+e.getKey());  
            System.out.println("value:"+e.getValue());     
        }     
        for( Iterator<Entry<Integer, Integer>> i = mm.entrySet().iterator(); i.hasNext(); ){      
            Entry<Integer, Integer> e = i.next();  
            System.out.println("key:"+e.getKey());  
            System.out.println("value:"+e.getValue());  
        }  
          
          
        Map map = new HashMap();  
  
        Irerator iterator = map.entrySet().iterator();  
  
        while(iterator.hasNext()) {  
            Map.Entry entry = iterator.next();  
            Object key = entry.getKey();  
        }  
          
        Set keySet= map.keySet();  
  
        Irerator iterator = keySet.iterator;  
  
        while(iterator.hasNext()) {  
            Object key = iterator.next();  
            Object value = map.get(key);  
        }  
          
        //另外，还有一种遍历方法是，单纯的遍历value值，Map有一个values方法，返回的是value的Collection集合。通过遍历collection也可以遍历value,如  
        Collection c = map.values();  
  
        Iterator iterator = c.iterator();  
  
        while(iterator.hasNext()) {  
           Object value = iterator.next();   
       }  
  
    }  
}