Java indexOf() Method: Finding Elements in a Set

[0rthodontist]

In Java, I am looking for a collection that will test if a given element is in a set, using the equal() method defined for the element. If it is in the set, I need the collection to give me the actual occurrence of the object from the set. Vector will do this for me via the indexOf() method, but the problem is that the search function in Vector is too slow. TreeSet will do the test for elementhood but won't retrieve the object. I also need to add additional objects to this set fairly regularly (a few tens of thousands of objects). I don't think the Java API has anything that does exactly what I want, but maybe there is another API that does? I'd rather not implement it myself.

 

[Aaron Bex]

The Java collections API does not have a collection that will do exactly what you are looking for. However, there are some third-party libraries that might be able to help. One such library is Guava, which provides a MultiSet class that allows you to store multiple copies of the same element and retrieve them using the equal() method. The MultiSet is backed by a HashMap, meaning that it should provide good performance when adding and retrieving elements.

 

[piercas]

it is important to carefully consider the trade-offs between different data structures and their corresponding methods in order to achieve optimal performance for your specific needs. In the case of finding elements in a set using the equal() method, it seems that neither Vector nor TreeSet fully meet your requirements.

One potential solution could be to use a HashMap, which allows for efficient retrieval of objects based on a given key. In this case, you could use the object itself as the key and store the object as the value. This would allow for quick lookup of an object and its corresponding occurrence in the set.

However, as you mentioned, adding tens of thousands of objects to a set regularly could potentially impact the performance of a HashMap. In this case, you may want to consider using a data structure specifically designed for handling large amounts of data, such as a Bloom filter or a Skip List.

Ultimately, the best approach will depend on your specific needs and the trade-offs you are willing to make. It may be worth experimenting with different data structures and methods to find the most efficient solution for your particular use case.