java - Why does a non-empty List throw a Null Pointer Exception? -


i have list array 'details'. 

list<historydetails> details

where historydetails object containing strings.

when check size gives me positive value.

details.size()

but when try access element throws null pointer exception.

details.get(0).getfirstelement();   attempt invoke virtual method 'java.lang.string com.historydetails.getfirstelement()' on null object reference

i invoking element @ next line check size. hence, nothing should reset. wrong?

a list details having many items can have first item null object. before using item check null.

if(details.get(0)!=null){ details.get(0).getfirstelement(); }

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