java - Deleting a single linked list by just making head = null? -

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why can't make head=null delete complete linked list?

3 = head > 1 > 2 > 4 > null

by making head = null, jvm take care of it.as head node not referenced variable , should garbage collected.

what wrong solution?

note: i'm aware of correct solution delete complete link list i'm curious why can't make head=null delete complete linked list?

here's code of java.util.linkedlist.clear(), verbatim:

public void clear() {     // clearing of links between nodes "unnecessary", but:     // - helps generational gc if discarded nodes inhabit     //   more 1 generation     // - sure free memory if there reachable iterator     (node<e> x = first; x != null; ) {         node<e> next = x.next;         x.item = null;         x.next = null;         x.prev = null;         x = next;     }     first = last = null;     size = 0;     modcount++; }

the comment answers question. it's unnecessary. can gc, , can make more objects eligible gc sooner if there iterator references 1 of nodes: referenced node still won't eligible gc, nodes after , before referenced node be, since they're not referenced anymore.

note developer chose make clear() method slower (o(n) instead of o(1)), make gc faster , reduce "memory leaks". inverse choice.

also note might never call clear(), , stop referencing object of type linkedlist, leaving nodes linked together. gc collect nodes if none of them reachable through reference chain gc root. that's happens 99% of times use list.


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