java - ArrayList declaration and handling -

i use arraylist in java software , insist program has clean possible.

i have ambiguity in arraylist variable declaration , usage.

so, is, among these 3 arraylist usages, correct way have choose?

case 1:

list<object> l = some_function();

case 2:

    list<object> l  = new arraylist<object>();     l = some_function();     //staff     l.clear()

case 3:

 list<object> l = null;  l = some_function();  //staff  l.clear()

function:

list<object> some_function(){ list<object> list = new ayyarlist<object>(); //staff return list; }

my question function is: java clear list variable automatically, or have clean using clear() api , how then? }

in opinion, case 1 better. 2nd case create unnecessary arraylist object, lost when assign method return value.

does java clear list variable automatically, or have clean using clean() api , how then?

java won't clear list, have clear it, check api, arraylist#clear()

how can clear list manually if declared inside function , should use later outside function(its outputs)

you have assign returned list temporary list, can clear list.

list<object> returnedlist = some_function();  //stuff  returnedlist.clear()

list<object> some_function() {      list<object> list = new ayyarlist<object>();      //stuff      return list; }

Silver