Does NJ law prohibit alcohol consumption in public parks?
TITLE 7 OF THE NEW JERSEY ADMINISTRATIVE CODE.
7:2-2.6 Alcoholic beverages prohibited
A person shall not possess and/or consume alcoholic beverages on lands and waters under the jurisdiction of the State Park Service except where the sale, use or possession is specifically approved by the Director of the Division of Parks and Forestry or the Assistant Director of the Division for the State Park Service.
There is no statewide law governing non-state parks - like city and county parks for example. These entities are free to regulate as they see fit. For those rules you will need to inquire specifically.