Android Strong Pointer Weak Pointer Get Free Info
Class child_foo. Sp theObj TheClass must inherit from class RefBase.
Simple reference count only strong reference count.
Android strong pointer weak pointer. Lock on a weak pointer returns a strong pointer. Sp是Strong pointerwp是Weak pointer 是实现android C 自动内存分配和回收避免内存泄漏的机制类似于java的垃圾回收机制 android 中的强指针和弱指针 hellofeiya的专栏. In this tutorial youll learn Weak Vs Strong Ref Cursor Normal cursor Vs Ref CursorPLSQL Procedural LanguageStructured Query Language is Oracle Co.
Smart pointer in Android. Ok you should tell us that- less than 1 of people who ask Android questions are working on AOSP they mean user level android. In the Android implementation of strong pointer any strong-pointer based object must inherit refbase ie.
Stdweak_ptr models temporary ownership. TYPE cursor_type_name IS REF CURSOR. Class foo.
Dec strong counter dec weak counter 如果是最后一个强指针调用子类接口进行清理工作. Template sp. This is how you access the weak pointer.
A shared_ptr is a container for raw pointers. So the counter is incremented each time a new pointer points to the resource and decremented when the destructor of the object is called. An object referenced only by weak references meaning every chain of references that reaches the object includes at least one weak reference as a link is considered weakly reachable and can be treated as unreachable and so may.
In computer programming a weak reference is a reference that does not protect the referenced object from collection by a garbage collector unlike a strong reference. The place to start looking for the implementation is the framework RefBaseh which is a bit twisty for a C newcomer. Use weak reference count.
Theyre generally hard to track down. Below is the syntax of cursor variable declaration and note that Return type is optional and it decides whether cursor type is Strong or weak. If the object is no longer valid its been deleted etc then the strong pointer will be NULL otherwise it will point at the object.
The fundamental conceptual difference between a naked pointer and a weak_ptr is that if the object pointed to is destroyed the naked pointer wont tell you about it. Sp is Strong Pointer wp is Weak Pointer.
Inc weak counter inc strong counter 如果是第一个强指针调用子类接口进行初始化工作. Const sp. None of what youre fiddling with is part of the public API defined by the NDK which means.
It maintains the reference count of its contained pointer in cooperation with all copies of the shared_ptr. A pointer to an object that doesnt exist. When an object needs to be accessed only if it exists and it may be deleted at any time by someone.
However if it is in. This requirement can be seen in the code for one of sp s methods.
Sp item new child_foo. Public foo. I cannot figure out the following difference in Android framework in C as.
If RETURN type clause is missing from cursor type declaration then reference type is weak else Strong. This is called a dangling pointer. So yes strong and weak pointers are different smart pointer implementations and do about the same thing- when a pointer goes out of scope so long as at least one strong pointer references it it will not be freed.
There are three smart pointers available in Android. Stdweak_ptr is a smart pointer that holds a non-owning weak reference to an object that is managed by stdshared_ptr. This video demonstrates an issue with C shared_ptr and how to overcome that issue with the use of weak_ptrIn case your design has a circular dependency is.
Then the strong count of item is 2. Use strong reference count. It is a reference counting ownership model ie.
Design of smart pointersA very important difference between Java and C is that Java does not have the pointer concept but does notPointers are used internally to hide them packaging so that developers do not have to worry about pointers. They came into being as part of the Binder IPC implementation.
It must be converted to stdshared_ptr in order to access the referenced object.
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