可以构造函数返回一个null对象吗？ [英] Can constructor return a null object?

问题描述

在查看一些旧代码时，我遇到了这个gem：

While looking through some old code I came across this gem:

MyObject o = new MyObject("parameter");
if (o == null) o = new MyObject("fallback parameter");

第二行在Eclipse中被标记为死代码，我明白为什么。没有异常似乎被明确抛出，并且 MyObject 构造函数不可能抛出任何种类的异常（例如 NullPointerException s）。

The second line is marked in Eclipse as dead code, and I understand why. No exception seems to be explicitly thrown, and it isn't possible for the MyObject constructor to throw any kind of exception (such as NullPointerExceptions).

我的问题是为什么有空检查？以前是否可能在旧版本的Java中为构造函数返回null？或者这只是无用的和死代码？

My question is why there is a null check? Was it previously possible in an old version of Java for a constructor to return null? Or is this simply useless and dead code?

推荐答案

代码在任何版本的java都死了。构造函数不能返回 null ，即使从构造函数抛出异常，下一行也不会被调用。

The code is dead in any version of java. It's not possible for a constructor to return null and even if an exception would be thrown from the constructor, the next line won't be called.

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