//定义一个泛型集合
Map<String, String> map = new HashMap<String, String>();
//通过Map的put方法向集合中添加数据
    map.put("001", "刘备");
    map.put("002", "曹操");
    map.put("003", "孙权");

//调用KeySet方法放回一个Set接口类型
    Set<String> set = map.keySet();
    //使用for增强来取出key和value
    for (String item : set) {
      System.out.println("Key是：" + item + ";Value值是：" + map.get(item));
    }

Collection<String> con = map.values();
    for (String item : con) {
      System.out.println("Value值是：" + item);
    }

Set<Entry<String, String>> setentry = map.entrySet();
    for (Entry<String, String> item : setentry) {
      System.out.println("Key是：" + item.getKey() + ";Value值是："
          + item.getValue());
    }

Iterator<String> it = map.keySet().iterator();
//如果仍有元素可以迭代，则返回 true。    while (it.hasNext()) {     //获取Key值
   String key = it.next();   System.out.println("Key是：" + key + ";Value值是：" + map.get(key));
   }

Iterator<String> it1 = map.values().iterator();
    while (it1.hasNext()) {
      String value = it1.next();
      System.out.println("Value值是：" + value);
    }

Iterator<Entry<String, String>> it2 = map.entrySet().iterator();
    while (it2.hasNext()) {
      Entry<String,String> entry=it2.next();
      System.out.println("Key是：" + entry.getKey() + ";Value值是：" + entry.getValue());
    }