@b.long I came across this post looking for a very particular solution to easily verify if a String's content has a JSON (object/array). I couldn't find any library that would suit my needs.
JSON Tools project or json-schema-validator though offer a lot are too big for my needs. Thus I did implement my own solution that is build on top of JSON.org reference implementation of JSON in Java.
I have already been using the JSON.org's code and technically all this functionality was already there, thus I added this very simple functionality reusing its code.
I use it to easily test if the String returned by methods querying my database are formatted in proper JSON which otherwise if badly formatted and posted to a client might cause it to stop working.
Hope this is of use to you as it is to me.
