I'm not sure, but it sounds like soursop, also known as custard apple. The Indonesian name is sirsak . But jackfruit (Indonesian nangka ) is completely different inside.

Nangka is a green knobbly fruit about double the size of an American football (you do not want to be under the tree when one drops off). Inside are lots of rubbery bright yellow pouches each containing a seed about the size of a peach stone. These pouches are what you eat. Raw they are delicious. Cooked, I find them revolting, they congeal into a pulsating purplish-brown goo. This is the basis for the Yogyakarta delicacy of gudeg, which I have never been able to bring myself to try.

Bingley

Bingley