Rotation constant: 0 degree rotation (natural orientation)

Rotation constant: 180 degree rotation.

Rotation constant: 270 degree rotation.

Rotation constant: 90 degree rotation.

Describe the kinds of special objects contained in this Parcelable‘s marshalled representation.

Release the local reference to the server-side surface. Always call release() when you‘re done with a Surface. This will make the surface invalid.

   getClass().getName()+‘@‘+Integer.toHexString(hashCode())

See Writing a useful toString method if you intend implementing your own toString method.

Posts the new contents of the Canvas to the surface and releases the Canvas.

Invoked when the garbage collector has detected that this instance is no longer reachable. The default implementation does nothing, but this method can be overridden to free resources.
 注意对象重写finalize 值得注意的它比不重写的对象是更昂贵。当这个对象不再可读时，Finalizers或许运行很长一段时间，这依赖于内存的压力，因此依赖这个方法来实现cleanup是很不好的一个注意。另外也要注意finalizers运行在一个单独的VM wide finalizer线程，因此在一个finalizer中进行一个堵塞性的工作是非常不好的。一个finalizer通常仅仅在一个类有一个本地的peer而且需要调用一个本地方法去销毁那个同龄的peer。即使如此，最好提供一个明确的close方法（并实现Closeable），并且坚持这个callers人为的处理这个instance。这个有时工作的很好，例如对于files，但是对于一些像BigInteger这些典型的调用代码则会处理很多临时性的问题。不幸的是，创建很多临时性的代码是最烂的代码之一，就view的 单finalizer线程而言。

Note that objects that override finalize are significantly more expensive than objects that don‘t. Finalizers may be run a long time after the object is no longer reachable, depending on memory pressure, so it‘s a bad idea to rely on them for cleanup. Note also that finalizers are run on a single VM-wide finalizer thread, so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary for a class that has a native peer and needs to call a native method to destroy that peer. Even then, it‘s better to provide an explicit close method (and implement Closeable), and insist that callers manually dispose of instances. This works well for something like files, but less well for something like a BigInteger where typical calling code would have to deal with lots of temporaries. Unfortunately, code that creates lots of temporaries is the worst kind of code from the point of view of the single finalizer thread.
如果你必须finalizers，考虑一下至少提供你自己的ReferenceQueue并且有你自己的队列线程。

If you must use finalizers, consider at least providing your own ReferenceQueue and having your own thread process that queue.
不像构造方法，finalizers不是自动的链接上的。你要自己负责调用super.finalize()方法。

Unlike constructors, finalizers are not automatically chained. You are responsible for calling super.finalize() yourself.
由finalizers抛出的未捕捉的异常，被忽略。并且不决定这个finalizer线程。看 Effective Java Item7的“Avoid finalizers”获得更多的内容。

Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread.
See Effective Java Item 7, "Avoid finalizers" for more.