Collections and exceptions

[p hasini]

Please clarify.

1. In what situations we write try/finally without a catch.

2. How can we avoid duplicates in a list

3. How can we make an ArrayLsit synchronized explicitly.

[Seetharaman Venkatasamy]

p hasini wrote:1. In what situations we write try/finally without a catch.

if there in no need to catch exception and need to de-allocate resource like db connection though there is an exception

p hasini wrote:2. How can we avoid duplicates in a list

you cant . if you want to avoid duplicates *use Set*

p hasini wrote:3. How can we make an ArrayLsit synchronized explicitly.

java.util.Collections class has a method for this. but i suggest you to prefer *java.util.concurrent.CopyOnWriteArrayList*

hth

[Rob Spoor]

Seetharaman Venkatasamy wrote:

p hasini wrote:2. How can we avoid duplicates in a list

you cant . if you want to avoid duplicates *use Set*

Well you can, but you'll need to call contains first:

if (!list.contains(value)) list.add(value);

But you can't subclass a List implementing class and add override the add methods to add this check since it breaks the contract for List -- it explicitly allows duplicates. A LinkedHashSet is a good alternative for a collection without duplicates that maintains insertion order.