Java中的非泛型集合 - 任何用途？

Question

是否有任何情况下最好在Java中使用非泛型集合而不是通用集合（或者它们仅为向后兼容性而存在）？

Answer 1

Absolutely not. In the case in which you can't infer types at declaration time, use a ? as a type specifier - that's what it is for. (There are cases where using ? would restrict you from invoking certain methods, such as List.add() . In such cases, you can find a more restrictive type specifier; Object usually works).

The non-generic usage is still supported because, technically, there is nothing wrong in not using it; you're just going to end up writing more casting instructions and put yourself in a higher risk for ClassCastException 's, but it is technically legitimate as far as the specification is concerned.

Overall, there is no case (that I can think of) where avoiding generics is "better than" using them. At the worst case (when you must use ? or Object at declaration time), both approaches are equal.