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
Be careful about what you do in a finalize(). Especially if you are using it for things like calling close() to ensure that resources are cleaned up. We ran into several situations where we had JNI libraries linked in to the running java code, and in any circumstances where we used finalize() to invoke JNI methods, we would get very bad java heap corruption. The corruption was not caused by the underlying JNI code itself, all of the memory traces were fine in the native libraries. It was just the fact that we were calling JNI methods from the finalize() at all.
这是JDK 1.5，它仍然在广泛使用。
直到很久以后，我们才发现出了问题，但最终罪魁祸首始终是使用JNI调用的finalize()方法。
其他回答
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。
class MyObject {
Test main;
public MyObject(Test t) {
main = t;
}
protected void finalize() {
main.ref = this; // let instance become reachable again
System.out.println("This is finalize"); //test finalize run only once
}
}
class Test {
MyObject ref;
public static void main(String[] args) {
Test test = new Test();
test.ref = new MyObject(test);
test.ref = null; //MyObject become unreachable，finalize will be invoked
System.gc();
if (test.ref != null) System.out.println("MyObject still alive!");
}
}
====================================
结果:
This is finalize
MyObject still alive!
=====================================
所以你可以在finalize方法中使一个不可达的实例可达。
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()对于捕获资源泄漏非常有用。如果资源应该关闭，但没有关闭，则将资源未关闭的事实写入日志文件并关闭。通过这种方式，您可以删除资源泄漏，并提供一种方法来知道它已经发生，以便您可以修复它。
我从1.0 alpha 3(1995)开始就一直在用Java编程，我还没有覆盖任何东西的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.
