java - NullPointerException when trying to convert list back into an array -

java - NullPointerException when trying to convert list back into an array -

i'm getting npe when trying convert list array. debugged through , found list getting value null.

why happening , more importantly how prepare issue?

list<string> attrlist = new linkedlist<string>(arrays.aslist(attrarray)) //i loop through , remove unnecessary elements attrarray = attrlist.toarray(attrarray); //next line uses attrarray , throwing npe. here's found through debugging, attrlist = [1, 2, 3] attrarray = [1, 2, 3, null]

try replacing

attrarray = attrlist.toarray(attrarray);

with

attrarray = attrlist.toarray(new string[attrlist.size()]);

i think work, because have right is

list<string> attrlist = new linkedlist<string>(arrays.aslist(attrarray)); // loop through , remove unnecessary elements attrarray = attrlist.toarray(attrarray);

and javadoc of list#toarray(t[] a) states (highlights me):

if list fits in specified array room spare (i.e., array has more elements list), element in array next end of list set null. (this useful in determining length of list if caller knows list not contain null elements.)

java arrays list nullpointerexception