A destructor is a method which is invoked just before the memory of the object is released. Use of destructors is for Resource Acquisition Is Initialisation (RAII).
Because Java is a garbage collected language you cannot predict when (or even if) an object will be destroyed. Hence there is no direct equivalent of a destructor. There is an inherited method called finalize, but this is called entirely at the discretion of the garbage collector. So for classes that need to explicitly tidy up, the convention is to define a close method and use finalize only for sanity checking (i.e. if close has not been called do it now and log an error).