It is completely impossible to deep-copy an arbitrary object. For example, how would you handle a Control or a FileStream or an HttpWebResponse? Your code cannot know how the object works and what its fields are supposed to contain. Do not do this. It’s a recipe for disaster.
Firstly, you never set an object to null. That concept has no meaning. You can assign a value of null to a variable, but you need to distinguish between the concepts of “variable” and “object” very carefully. Once you do, your question will sort of answer itself 🙂 Now in terms of “shallow copy” vs … Read more
No. A shallow copy in this particular context means that you copy “references” (pointers, whatever) to objects, and the backing store of these references or pointers is identical, it’s the very same object at the same memory location. A deep copy, in contrast, means that you copy an entire object (struct). If it has members … Read more
int[][] copy = new int[nums.length][]; for (int i = 0; i < nums.length; i++) { copy[i] = new int[nums[i].length]; for (int j = 0; j < nums[i].length; j++) { copy[i][j] = nums[i][j]; } } You can replace the second loop with System.arraycopy() or Arrays.copyOf().
Presumably, it is because deepCopy does not begin with the prefix copy. So you may want to change to something like copyWithDeepCopiedValues (or something like that), and then see if the analyzer flags that. Update As Alexsander noted, you can use attributes to denote reference counting intent. This should (IMO) be the exception to the … Read more
A couple of years ago, I wrote a few category methods for exactly the same reason, transforming a whole tree of user defaults to mutable. Here they are – use them at your own risk! 🙂 // // SPDeepCopy.h // // Created by Sherm Pendley on 3/15/09. // #import <Cocoa/Cocoa.h> // Deep -copy and -mutableCopy … Read more
From the link here Shallow copies duplicate as little as possible. A shallow copy of a collection is a copy of the collection structure, not the elements. With a shallow copy, two collections now share the individual elements. Deep copies duplicate everything. A deep copy of a collection is two collections with all of the … Read more
Forget about deep copy, even shallow copy isn’t safe, if the object you’re copying has a property with enumerable attribute set to false. MDN : The Object.assign() method only copies enumerable and own properties from a source object to a target object take this example var o = {}; Object.defineProperty(o,’x’,{enumerable: false,value : 15}); var ob={}; … Read more
I think that Pympler has already beaten you to the punch on this one. From their documentation: >>> from pympler.asizeof import asizeof >>> obj = [1, 2, (3, 4), ‘text’] >>> asizeof(obj) 176 The source code can be found here.
Take a look at Deep Cloning, on Google Code you can find a library. You can read it on https://github.com/kostaskougios/cloning. How it works is easy. This can clone any object, and the object doesnt have to implement any interfaces, like serializable. Cloner cloner = new Cloner(); MyClass clone = cloner.deepClone(o); // clone is a deep-clone … Read more