add ArrayList to multiple ArrayList in java -

hi have problem arraylists have 3 lists

arraylist1<integer>=[1,2,3] arraylist2<integer>=[] arraylist3<arraylist<integer>>=[]

arraylist1 elements used adding values arraylist2 example

for(int i:arraylist1) { for(int a=0;a<i;a++) { arraylist2.add(a); } }

and works fine no problem there want every element in arraylist1 add together arraylist2 arraylist3 have come not work

 for(int i:arraylist1)     {       for(int a=0;a<i;a++)       {         arraylist2.add(a);       }       arraylist3.add(arraylist2);     }

simply utilize addall, , collections.fill.

example

list2.addall(list1); list3 = new arraylist<arraylist<integer>>(list1.size()); collections.fill(list3, list2);

note list3 filled same instance of list2.

this means every alter list2 reflected in each element of list3.

if not behavior you're expecting, iterate on length of list1 , add together new arraylist<integer>(list2).

java

Jaimee