Today, I had a huge Json in my app and I wanted to fetch all these values in a general way. I also wanted to parse Json for only one time to avoid try/catch each time I access any value. So, first thing I had in mind was to convert the JSONObject in the HashMap or Map<> etc.

So if you are using Gson in your apps for json mapping, then you can use this one line code for conversion.

Map<String, Object> mapObj = new Gson().fromJson(
  myJsonObjectString, new TypeToken<HashMap<String, Object>>() {}.getType()
);

This will give you a Map object and you can access the values using this code.

String strValue = (String) mapObj.get(myJsonKey);
String contains = mapObj.containsKey(myJsonKey);

References

https://stackoverflow.com/questions/21720759/convert-a-json-string-to-a-hashmap