There are totally 5 objects created on the heap, NOT 8 objects. I think you have assumed that for new grab1, 4 objects have been created. Please note that it is just a single array object and not 4 objects. The 5 objects are as follows: 1 grab1 array object 4 grab1 objects
Out of these 5 objects, 3 grab1 objects (i.e. the first 3 created grab1 objects) are eligible for garbage collection. The last grab1 object and the grab1 array object will remain active and are not eligible for garbage collection. Please note that inside the method "f", you set array to null. This actually sets the copy of the reference to be set to null and the actual array reference in the main method remains unaffected and is not set to null.