1 public class MultiMap {
2
3 private HashMap<String, List<String>> maps = new HashMap<String, List<String>>();
4 //创建put方法
5 public void put(String key, String value) {
6 //如果此映射不包含对于指定键的映射关系
7 if (!maps.containsKey(key)) {
8 maps.put(key, new ArrayList<String>());
9 }
10 maps.get(key).add(value);
11 }
12 public List<String> get(String key){
13 if(maps.containsKey(key)){
14 return maps.get(key);
15 }else{
16 return new ArrayList<String>();
17 }
18 }
19
20 public Set<String> keySet(){
21 return maps.keySet();
22 }
23 }