Map<String,List<String>>转 Map<String,String>

可以通过遍历Map<String,List<String>>，将List<String>转化为String，然后将其放入新的Map<String,String>中。具体实现如下所示：

Map<String, List<String>> map1 = new HashMap<>();
Map<String, String> map2 = new HashMap<>();
for (Map.Entry<String, List<String>> entry : map1.entrySet()) {
    String key = entry.getKey();
    List<String> valueList = entry.getValue();
    StringBuilder sb = new StringBuilder();
    for (String value : valueList) {
        sb.append(value);
    }
    map2.put(key, sb.toString());
}