面试题-给定一个“flatten”Dictionary对象，根据键转换成嵌套字典对象

题目：

给定一个“Flatten” Dictionary 对象其键是点分割的，例如:{"A":1,"B.A":2,"B.B":3,"CC.D.E":4,"CC.D.F":5},实现一个函数，将其转换 为一个嵌套的字典对象，根据上面例子，嵌套对象结果为{A:1,"B":{"A":2,"B":3},"CC":{"D":{"E":4,"F":5}}}

答案

/** * {A：1, B.A:2 B.B:3 CC.D.E:4 CC.DF:5} * @param args */ public static void main(String[] args) { Map<String, Integer> flatten = new HashMap<>(); //生成例子数据 flatten.put("A",1); flatten.put("B.A",2); flatten.put("B.B",3); flatten.put("CC.D.E",4); flatten.put("CC.D.F",5); Map<String, Object> newFlatten = new HashMap<>(); flatten.forEach((key,val)->{ recursion(key,newFlatten, val); }); System.out.println(flatten); System.out.println(newFlatten); } /** * 递归方法 * @param key * @param map * @param val */ public static void recursion(String key ,Map<String,Object> map,Integer val){ boolean contains = key.contains("."); //最后一个赋值 if(!contains){ map.put(key,val); }else{ String beforeKey = StrUtil.subBefore(key, ".", false); String afterKey = StrUtil.subAfter(key, ".", false); HashMap<String, Object> newMap = new HashMap<>(); if (!map.containsKey(beforeKey)){ map.put(beforeKey,newMap); }else { newMap = (HashMap<String, Object>) map.get(beforeKey); } recursion(afterKey,newMap,val); } }