list集合，map集合遍历

 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;   

 /**
 *遍历集合List
  * @author Men、叔
 *  Email 844357411@qq.com  【Men 叔 Java厂】：http://jq.qq.com/?_wv=1027&k=cfqLhZ
  */
 public class Demo {   

     /**
      * @param args
      */
     public static void main(String[] args) {   

         List list = new ArrayList();
         list.add("aaa");
        list.add("bbb");
         //1:利用下标
      for(int i =  ; i< list.size();i++){   

             System.out.println(list.get(i));
        }
         //2:for- each
         for(Object o:list){
           System.out.println(o);
         }
         //3:迭代器
        Iterator it = list.iterator();
        while(it.hasNext()){
           System.out.println(it.next());
         }
        //4:Object数组
       Object o[];
         o = list.toArray();
         for(int i =   ; i <o.length;i++){
         System.out.println(o[i]);
        }
        //5:toString
        System.out.println(list.toString());   

     }   

 }
 public class Demo{
 public static void main(String[] args) {

   Map<String, String> map = new HashMap<String, String>();
   map.put("", "value1");
   map.put("", "value2");
   //1：普遍使用，二次取值
   System.out.println("通过Map.keySet遍历key和value：");
   for (String key : map.keySet()) {
    System.out.println("key= "+ key + " and value= " + map.get(key));
   }

   //2:迭代器遍历
   System.out.println("通过Map.entrySet使用iterator遍历key和value：");
   Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
   while (it.hasNext()) {
    Map.Entry<String, String> entry = it.next();
    System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
   }

   //3：foreach 推荐，尤其是容量大时
   System.out.println("通过Map.entrySet遍历key和value");
   for (Map.Entry<String, String> entry : map.entrySet()) {
    System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
   }

   //
   System.out.println("通过Map.values()遍历所有的value，但不能遍历key");
   for (String v : map.values()) {
    System.out.println("value= " + v);
   }
  }
 }