How to make a deep copy of Java ArrayList [duplicate]
Cloning the objects before adding them. For example, instead of newList.addAll(oldList); for(Person p : oldList) { newList.add(p.clone()); } Assuming clone is correctly overriden inPerson.
deep-copy
How do I do a deep copy of a 2d array in Java?
Yes, you should iterate over 2D boolean array in order to deep copy it. Also look at java.util.Arrays#copyOf methods if you are on Java 6. I would suggest the next code for Java 6: public static boolean[][] deepCopy(boolean[][] original) { if (original == null) { return null; } final boolean[][] result = new boolean[original.length][]; for … Read more
Copying nested lists in Python
For a more general solution that works regardless of the number of dimensions, use copy.deepcopy(): import copy b = copy.deepcopy(a)
std vector C++ — deep or shallow copy
You are making a deep copy any time you copy a vector. But if your vector is a vector of pointers you are getting the copy of pointers, not the values are pointed to For example: std::vector<Foo> f; std::vector<Foo> cp = f; //deep copy. All Foo copied std::vector<Foo*> f; std::vector<Foo*> cp = f; //deep copy … Read more
Kotlin data class copy method not deep copying all members
The copy method of Kotlin is not supposed to be a deep copy at all. As explained in the reference doc (https://kotlinlang.org/docs/reference/data-classes.html), for a class such as: data class User(val name: String = “”, val age: Int = 0) the copy implementation would be: fun copy(name: String = this.name, age: Int = this.age) = User(name, … Read more
How to copy all items from one array into another?
The key things here are The entries in the array are objects, and You don’t want modifications to an object in one array to show up in the other array. That means we need to not just copy the objects to a new array (or a target array), but also create copies of the objects. … Read more
How create a new deep copy (clone) of a List?
You need to create new Book objects then put those in a new List: List<Book> books_2 = books_1.Select(book => new Book(book.title)).ToList(); Update: Slightly simpler… List<T> has a method called ConvertAll that returns a new list: List<Book> books_2 = books_1.ConvertAll(book => new Book(book.title));
Deep copying an NSArray
As the Apple documentation about deep copies explicitly states: If you only need a one-level-deep copy: NSMutableArray *newArray = [[NSMutableArray alloc] initWithArray:oldArray copyItems:YES]; The above code creates a new array whose members are shallow copies of the members of the old array. Note that if you need to deeply copy an entire nested data structure … Read more
Why and when to use angular.copy? (Deep Copy)
Use angular.copy when assigning value of object or array to another variable and that object value should not be changed. Without deep copy or using angular.copy, changing value of property or adding any new property update all object referencing that same object. var app = angular.module(‘copyExample’, []); app.controller(‘ExampleController’, [‘$scope’, function($scope) { $scope.printToConsole = function() { … Read more
How do I copy a hash in Ruby?
The clone method is Ruby’s standard, built-in way to do a shallow-copy: h0 = {“John” => “Adams”, “Thomas” => “Jefferson”} # => {“John”=>”Adams”, “Thomas”=>”Jefferson”} h1 = h0.clone # => {“John”=>”Adams”, “Thomas”=>”Jefferson”} h1[“John”] = “Smith” # => “Smith” h1 # => {“John”=>”Smith”, “Thomas”=>”Jefferson”} h0 # => {“John”=>”Adams”, “Thomas”=>”Jefferson”} Note that the behavior may be overridden: This … Read more