请问一下android下软/弱引用的一个问题

Question

我对软/弱引用看了也不少博客,但是还是有一点疑问,尤其是android 2.3 之后的软/弱引用机制
尝试搜索无果后,来这里请教一下,问题应该很简单,但是对我来说很困惑有点绕不过来弯.

谢谢

ViewStub 和其他很多地方都有用到WeakReference
弱引用不是在系统GC的时候如果它只被一个软引用所引用,那么它将会被回收吗?

在ViewStub的源码中,在inflate() 一个ViewStub的之后
同时将inflate()完毕的view添加至新创建的WeakReference 中,
那么这个view 不就只?被一个软引用所引用了吗?

如果这时系统GC 那么view是不是被回收了?那么下次想从WeakReference 中获取它的时候是不是又可能会为null ?从而导致错误?

或者说这种情况是不会被系统GC的? 望大鸟指教一下愚昧小弟

Answer 1

I think your understanding of the WeakReference mechanism is correct, but your understanding of the ViewStub code is wrong

WeakReference is used in ViewStub and many other places
Isn’t a weak reference that will be recycled if it is only referenced by a soft reference during system GC?

Will

In the source code of ViewStub, after inflate() a ViewStub,
add the inflate()ed view to the newly created WeakReference.
Isn’t this view just referenced by a soft reference?

The reference relationship of related objects is as follows:

inflate()第一次执行前:

parentView --强-> stubView

此时inflatedView还不存在

inflate()第一次执行后:
parentView --强-> inflatedView 
stubView --弱->inflatedView

此时parentView已经不引用stubView了，stubView在inflate()中用inflatedView替换了parentView中的自己

So inflatedView is still strongly referenced and will not be GC