Coding Suggestion

How i get a userTaskId?

I searched in Javadocs for a userTaskId method , and i dont find any direct method. its a value from 2 or more method calls? How i reach this value?
My objective is create a Tasks Shelf, anyone who take a task, can return it if dont wanna or simple view that task. and for that i needed a release task, the method needs userTaskId. and when take the task, another tasks became invisible until finish or return a task. using Hide Task method