Map转Map

将一个Map<String,Integer> 转换成Map<String,String>

1. //创建一个创建Map的公共方法
   private static <T> Map<String,T> newMap(String key,T val,Object...kv){
       Map<String,T> ans = new HashMap<>(8);
       ans.put(key,val);
       for(int i=0,size = kv.length; i< size; i+=2){
           ans.put(String.valueOf(kv[i]),(T)kv[i+1]);
       }
       return ans;
   }
   

2. 基本的for循环转换

   1. @Test
      public void forEachParse(){
          Map<String,Integer> map = newMap("k",1,"a",2,"b",3);
          Map<String,String> strMap = new HashMap<>(map.size);
          for(Map.Entry<String,Integer> entry: map.entrySet()){
              strMap.put(entry.getKey(),String.valueOf(entry.getValue()));
          }
      }
      

3. 容器的流式使用来实现转换

   1. @Test
      public void stream(){
          Map<String,Integer> map = newMap("k",1,"a",2,"b",3);
          Map<String,String> strMap = map.entrySet().stream().collect(
          	Collectors.toMap(Map.Entry::getKey,s->String.valueOf(s.getValue()),(a,b) ->a));
      }
      

4. Guava的transform方式

   1. @Test
      public void transfer(){
          Map<String,Integer> map = newMap("k",1,"a",2,"b",3);
          Map<String,String> strMap = Maps.transformValues(map,String::valueOf);
      }