不需要投射 findViewById 的结果吗? [英] No need to cast the result of findViewById?

问题描述

最近我发现 AndroidStudio 提醒我删除一些类转换.记得以前我们要对findViewById的结果进行强制转换，现在不用了.

Recently I found that AndroidStudio reminds me to remove some class cast. I remember that in the old time, we have to cast the result of findViewById, but now it's not necessary.

findViewById的结果还是View，所以我想知道为什么我们不需要cast这个类?

The result of findViewById is still View, so i want to know why we don't need to cast the class?

我找不到提到的任何文件，谁能找到任何文件?

I can't find any documents mentioned that, can anyone find any document?

推荐答案

从 API 26 开始，findViewById 对其返回类型使用推理，因此您不再需要强制转换.

Starting with API 26, findViewById uses inference for its return type, so you no longer have to cast.

旧定义:

View findViewById(int id)

新定义:

<T extends View> T findViewById(int id)

所以如果你的 compileSdk 至少是 26，这意味着你可以使用这个 :)

So if your compileSdk is at least 26, it means that you can make use of this :)

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