public static void main(String[] args) {
Map<String,String> map = new HashMap<String,String>();
map.put("1", "A");
map.put("2", "B");
map.put("3", "C");
map.put("4", "D");
map.put("5", "E");
List<String> keylist =new ArrayList<>(map.keySet());
for(String key:keylist ){
System.out.println(key);
}
//List<String> valuesList = (List<String>) map.values();
//map.values()返回的是collection,通过arrayList的构造方法可以实现
List<String> valuesList = new ArrayList<String>(map.values());
for(String str:valuesList){
System.out.println(str);
}
}