我一直在阅读很多关于finalize()的Java新手问题，并发现没有人真正清楚地表明finalize()是一种不可靠的清理资源的方法，这有点令人困惑。我看到有人评论说他们用它来清理连接，这真的很可怕，因为唯一接近于保证连接关闭的方法是最后实现try (catch)。
我没有学过CS，但我已经用Java专业编程近十年了，我从来没有见过有人在生产系统中实现finalize()。这并不意味着它没有用处，或者和我一起工作的人一直在做正确的事情。
所以我的问题是，实现finalize()有哪些用例不能通过语言中的另一个进程或语法更可靠地处理?
请提供具体的场景或您的经验，简单地重复Java教科书，或最终确定的预期用途是不够的，因为这不是这个问题的意图。
当前回答
iirc——你可以使用finalize方法作为实现昂贵资源池机制的一种手段——这样它们就不会得到GC了。
其他回答
自1998年以来，我一直在从事Java专业工作，但我从未实现过finalize()。一次也没有。
嗯，我曾经用它来清理没有返回到现有池的对象。
它们经常被转来转去，所以不可能知道什么时候能安全地放回泳池。问题在于，它在垃圾收集过程中带来了巨大的损失，远远超过了使用对象池节省的成本。在我拆除整个池，让所有内容都变得动态并完成之前，它已经投入了大约一个月的时间。
finalize()是对JVM的一个提示，建议在未指定的时间执行代码。当您希望代码莫名其妙地无法运行时，这是很好的方法。
在终结器中做任何重要的事情(基本上除了日志)在三种情况下也很好:
您希望打赌其他已完成的对象仍然处于程序其余部分认为有效的状态。 您希望向所有具有终结器的类的所有方法添加大量检查代码，以确保它们在终结后行为正确。 您希望意外地复活已完成的对象，并花费大量时间试图弄清楚为什么它们不起作用，和/或为什么它们在最终释放时没有最终完成。
If you think you need finalize(), sometimes what you really want is a phantom reference (which in the example given could hold a hard reference to a connection used by its referand, and close it after the phantom reference has been queued). This also has the property that it may mysteriously never run, but at least it can't call methods on or resurrect finalized objects. So it's just right for situations where you don't absolutely need to close that connection cleanly, but you'd quite like to, and the clients of your class can't or won't call close themselves (which is actually fair enough - what's the point of having a garbage collector at all if you design interfaces that require a specific action be taken prior to collection? That just puts us back in the days of malloc/free.)
Other times you need the resource you think you're managing to be more robust. For example, why do you need to close that connection? It must ultimately be based on some kind of I/O provided by the system (socket, file, whatever), so why can't you rely on the system to close it for you when the lowest level of resource is gced? If the server at the other end absolutely requires you to close the connection cleanly rather than just dropping the socket, then what's going to happen when someone trips over the power cable of the machine your code is running on, or the intervening network goes out?
免责声明:我以前在JVM实现上工作过。我讨厌终结者。
接受的答案列出了在finalize期间关闭资源的操作。
然而，这个答案表明，至少在使用JIT编译器的java8中，您会遇到意想不到的问题，有时甚至在您完成从对象维护的流中读取之前就调用了终结器。
所以即使在这种情况下，也不建议调用finalize。
一个简单的规则:永远不要使用终结器。
对象具有终结器(不管它执行什么代码)这一事实本身就足以导致相当大的垃圾收集开销。
摘自Brian Goetz的一篇文章:
Objects with finalizers (those that have a non-trivial finalize() method) have significant overhead compared to objects without finalizers, and should be used sparingly. Finalizeable objects are both slower to allocate and slower to collect. At allocation time, the JVM must register any finalizeable objects with the garbage collector, and (at least in the HotSpot JVM implementation) finalizeable objects must follow a slower allocation path than most other objects. Similarly, finalizeable objects are slower to collect, too. It takes at least two garbage collection cycles (in the best case) before a finalizeable object can be reclaimed, and the garbage collector has to do extra work to invoke the finalizer. The result is more time spent allocating and collecting objects and more pressure on the garbage collector, because the memory used by unreachable finalizeable objects is retained longer. Combine that with the fact that finalizers are not guaranteed to run in any predictable timeframe, or even at all, and you can see that there are relatively few situations for which finalization is the right tool to use.
