How to convert JSON string to Map <String, Set <String>> using Jackson JSON
I am aware of an implementation that converts a JSON string to Map<String, String>
via:
public <T1, T2> HashMap<T1, T2> getMapFromJson(String json, Class<T1> keyClazz, Class<T2> valueClazz) throws TMMIDConversionException {
if (StringUtils.isEmpty(json)) {
return null;
}
try {
ObjectMapper mapper = getObjectMapper();
HashMap<T1, T2> map = mapper.readValue(json, TypeFactory.defaultInstance().constructMapType(HashMap.class, keyClazz, valueClazz));
return map;
} catch (Exception e) {
Logger.error(e.getMessage(), e.getCause());
}
}
But I cannot expand it to convert my JSON to Map<String, Set<String>>
. The above method obviously doesn't work as it breaks up the elements of the Set and puts them in a list. Need help here! Thanks to
An example JSON string is shown below. This JSOn should be converted to Map<String, Set<CustomClass>>
.
{
"0": [
{
"cid": 100,
"itemId": 0,
"position": 0
}
],
"1": [
{
"cid": 100,
"itemId": 1,
"position": 0
}
],
"7": [
{
"cid": 100,
"itemId": 7,
"position": -1
},
{
"cid": 140625,
"itemId": 7,
"position": 1
}
],
"8": [
{
"cid": 100,
"itemId": 8,
"position": 0
}
],
"9": [
{
"cid": 100,
"itemId": 9,
"position": 0
}
]
}
+3
source to share
2 answers
Try the following:
JavaType setType = mapper.getTypeFactory().constructCollectionType(Set.class, CustomClass.class);
JavaType stringType = mapper.getTypeFactory().constructType(String.class);
JavaType mapType = mapper.getTypeFactory().constructMapType(Map.class, stringType, setType);
String outputJson = mapper.readValue(json, mapType)
+7
source to share