How to efficiently (performance) remove many items from List in Java?

Question

I have quite large List named items (>= 1,000,000 items) and some condition denoted by that selects items to be deleted and is true for many (maybe hal

Answer 1

Maybe a List isn't the optimal data structure for you? Can you change it? Perhaps you can use a tree where the items are sorted into in a way that deleting one node removes all items that meet the condition? Or that at least speed up your operations?

In your simplistic example using two lists (one with the items where i % 2 != 0 is true and one with the items where i % 2 != 0 is false) could serve well. But this is of course very domain dependent.