Omit duplicate object that has same value in a collection class

[jing-yi]

Good day...

Set is able to omit duplicate value.

But, let say an object carry two attributes: attribute 1 and attribute2 and later it is added to a collection class.

Is anyone of you able to omit the object with same attribute 1 and attribute2?

Object obj1 = new Object();
obj1.attribute1 = "abc";
obj1.attribute2 = "def";

collection.add(obj1);

Object obj2 = new Object();
obj2.attribute1 = "abc";
obj2.attribute2 = "def";

collection.add(obj2);

Here, I hope the collection variable would carry one obj only instead of 2 obj...

[Tolls]

Crossposted at OTN...don't have the link handy I'm afraid.
There's a few answers over there, so no point anyone here looking at this I suppose.