What else i can use instead of contains method of collection to find out the similar entry in the collection.As contains is a very heavy(time consuming) method to use.
Right now i am using contains like this
if (EntityTree.setMobileEnablerTxnList.contains(iMobileEnablerTxnList)) {
}
Here setMobileEnablerTxnList is a set.
The contains method is not necessarily very heavy (time consuming). For example if you use a HashSet it is rather fast. For a HashSet it will calculate the hashCode of the object, and only go over the objects in the corresponding 'bucket'. It will certainly not go over all elements (or you would have a very poor implementation of the hashCode method).
This can be seen in the source code of the HashSet#contains method, which ultimately calls the following code in HashMap:
final Entry<K,V> getEntry(Object key) {
int hash = (key == null) ? 0 : hash(key.hashCode());
for (Entry<K,V> e = table[indexFor(hash, table.length)];
e != null;
e = e.next) {
Object k;
if (e.hash == hash &&
((k = e.key) == key || (key != null && key.equals(k))))
return e;
}
return null;
}
This clearly shows it loops only over a limited set of objects.
See also this question for more information about a HashMap (which is used internally by a HashSet)
Last piece of advise: if you have performance problems, use a profiler to see where the actual bottleneck is located. I doubt it will be in the contains call.
The implementation of List.contains() iterates through the list checking if the target.equals(element).
If possible, put your list into a HashSet, whose contains() method always returns very quickly.
Using a HashSet would only be of benefit if you can reuse it, because the cost of filling it would tpyically be greater than executing List.contains().
You code code look like this:
Set set = new HashSet(EntityTree.setMobileEnablerTxnList);
if (set.contains(iMobileEnablerTxnList)) {
You would have to make sure that MobileEnablerTxnList implements hashCode() and equals() properly.
