java - The algorithm compares two lists, synchronization tables -

the algorithm compares 2 lists list, synchronization tables

i need synchronize local table table loaded server. decided compare 2 stages list (local list , server). initially, list sorted. remains landmark in comparing of id.

if id on local list is, , server not present, removal of entries local database (delete). if id equal local server , update (update). if id server there, , there no local, add (select). problem have in phase comparison, somewhere wrong, not foreseen.

i throw off comparison algorithm, began write, not finish image , example. please modify it. image example: http://c2n.me/3mmgizg

list<integer> server = new arraylist<>(); list<integer> local = new arraylist<>(); databasehandler db = new databasehandler(context);   iterator<integer> seriter = server.iterator(); iterator<integer> lociter = local.iterator();  int item1 = seriter.next(); int item2 = lociter.next(); while(seriter.hasnext()) {     if (item1 <item2) {         db.addcourse(item1);         item1 = seriter.next();     } else {         if (lociter.hasnext()) {             while (item2 < item1) {                db.deletecourse(item2);                item2 = lociter.next();             }             if (item1 == item2) {                 db.updatecourse(item1);                 item2 = lociter.next();                 item1 = seriter.next();             }         } else {             while(item1<item2) {                 db.addcourse(item1);                 item1 = seriter.next();             }             if (item1 == item2) {                 db.updatecourse(item1);                 item1 = seriter.next();             } else {                  db.deletecourse(item2 );                 continue other;             }        } } other:     while(item1>item2) {         db.addcourse(item1);         item1 = seriter.next();     } } 

i'm not sure understand you're saying. if want make local list = server list, follows:

for(int = 0; < server.size(); i++) {     local.set(i, server.get(i)); } 

this iterate through items in server arraylist , change them value in local arraylist