Java HashMap vs JSONObject – Comparing Java HashMap and JSONObject

This depends a lot on what you are trying to achieve: for flexibility, hash map is better. But the flexibility comes at a price: hash map is also larger and slower than a class with the identical number of strongly-typed fields.

• Hash map has larger memory footprint than a class with identical number of fields
• Hash map forces boxing on primitives
• Hash map is slower to create and access

There is also an impact on readability: when you business logic is specific to a class with a fixed number of fields, a special-purpose class clearly wins; when the fields are configured dynamically, hash table is your only option. You could also have a hybrid design, when an object uses a hash map for its storage internally, presents nicely named fields externally, and exposes semantics to add more "fields" as you go.

To summarize, before you decide to go with a hash map for its flexibility, you should decide if you really need all that flexibility in your design. Sometimes, the answer is "yes", and sometimes it is "no"; there is no "one size fits all" solution to this.

Use JSONObject constructor. DON"T CREATE YOUR OWN since you might miss some cases such when the value is an array.

JSONObject jsonObject = new JSONObject(hashMap);

This is actually a complete solution since it covers for corner cases such as where the value is an array. Thus, it will make it as JSONArray for you.