便利map

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;

public class testMap {
 public static void test(String[] args) {
     ArrayList<String> list = new ArrayList<String>();
     HashMap<Object,Object> hash = new HashMap<Object,Object>();
     TreeMap<Object,Object> treeMap = new TreeMap<Object,Object>();
     list.add("a");
     list.add("b");
     list.add("c");
   
     hash.put(3, 3);
     hash.put(4, 4);
     hash.put(5, 5);
     hash.put(6, 6);
     hash.put(1, 1);
     hash.put(2, 2);
   
     treeMap.put(1, 1);
     treeMap.put(2, 2);
     treeMap.put(3, 3);
     treeMap.put(4, 4);
     treeMap.put(5, 5);
     treeMap.put(6, 6);
   
     //list遍历
     for(String m: list){
      System.out.println(m);
     }
     // hashmap entrySet() 遍历
     for(Map.Entry<Object,Object> m: hash.entrySet()){
      System.out.println(m.getKey()+"---"+m.getValue());
     }
     //hashmap keySet() 遍历
     for(Object m: hash.keySet()){
      System.out.println(m+"---"+hash.get(m));
     }
     // treemap keySet()遍历
     for(Object m: treeMap.keySet()){
      System.out.println(m+"---"+treeMap.get(m));
     }
  }
 
 
 public static void main(String[] args) {  
     Map map = new HashMap();  
     map.put("1", "a");  
     map.put("2", "b");  
     Iterator it = map.entrySet().iterator();  
     while (it.hasNext()) {  
         Map.Entry entry = (Map.Entry) it.next();  
         String key = (String)entry.getKey();  
         String value = (String)entry.getValue();  
         System.out.println("key=" + key);  
         System.out.println("value=" + value);  
     }  
  
 }
}