Java拾遗

2020-04-28

好久不用Java，（其实现在也不用），只是在看一道之前的LeetCode题（之前用Java写的）的解法，回忆起了一些细节。

特开一贴，记录那些忘了的或者有点模糊的Java细节。

Why is Generic Array Creation not Allowed in Java?
List<String>[] ls = new ArrayList<String>[10]; ❌
List<String>[] ls = new ArrayList[10]; ✅

Why are arrays covariant but generics are invariant?
The reason is that every array knows its element type during runtime, while generic collection doesn't because of type erasure.

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