clone | 易学教程

Is it possible to clone html element objects in JavaScript / JQuery?

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问题 I am looking for some tips on how to solve my problem. I have a html element (like select box input field) in a table. Now I want to copy the object and generate a new one out of the copy, and that with JavaScript or jQuery. I think this should work somehow but I\'m a little bit clueless at the moment. Something like this (pseudo code): oldDdl = $(\"#ddl_1\").get(); newDdl = oldDdl; oldDdl.attr(\'id\', newId); oldDdl.html(); 回答1: Using your code you can do something like this in plain

What's the difference between Bitmap.Clone() and new Bitmap(Bitmap)?

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问题 As far as I can tell, there are two ways of copying a bitmap. Bitmap.Clone() Bitmap A = new Bitmap(\"somefile.png\"); Bitmap B = (Bitmap)A.Clone(); new Bitmap() Bitmap A = new Bitmap(\"somefile.png\"); Bitmap B = new Bitmap(A); How do these approaches differ? I\'m particularly interested in the difference in terms of memory and threading. 回答1: It is the common difference between a "deep" and a "shallow" copy, also an issue with the almost-deprecated IClonable interface. The Clone() method

How to clone an InputStream?

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问题 I have a InputStream that I pass to a method to do some processing. I will use the same InputStream in other method, but after the first processing, the InputStream appears be closed inside the method. How I can clone the InputStream to send to the method that closes him? There is another solution? EDIT: the methods that closes the InputStream is an external method from a lib. I dont have control about closing or not. private String getContent(HttpURLConnection con) { InputStream content =

How do I create a copy of an object in PHP?

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问题 It appears that in PHP objects are passed by reference. Even assignment operators do not appear to be creating a copy of the Object. Here\'s a simple, contrived proof: <?php class A { public $b; } function set_b($obj) { $obj->b = \"after\"; } $a = new A(); $a->b = \"before\"; $c = $a; //i would especially expect this to create a copy. set_b($a); print $a->b; //i would expect this to show \'before\' print $c->b; //i would ESPECIALLY expect this to show \'before\' ?> In both print cases I am

How create a new deep copy (clone) of a List<T>?

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问题 In the following piece of code, using System; using System.Collections.Generic; using System.Drawing; using System.Windows.Forms; namespace clone_test_01 { public partial class MainForm : Form { public class Book { public string title = \"\"; public Book(string title) { this.title = title; } } public MainForm() { InitializeComponent(); List<Book> books_1 = new List<Book>(); books_1.Add( new Book(\"One\") ); books_1.Add( new Book(\"Two\") ); books_1.Add( new Book(\"Three\") ); books_1.Add( new

clone() vs copy constructor vs factory method?

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I did a quick google on implementing clone() in Java and found: http://www.javapractices.com/topic/TopicAction.do?Id=71 It has the following comment: copy constructors and static factory methods provide an alternative to clone, and are much easier to implement. All I want to do is make a deep copy. Implementing clone() seems to make a lot of sense, but this highly google ranked article makes me a bit afraid. Here are the issues that I've noticed: Copy constructors don't work with Generics. Here's some pseudo-code that won't compile. public class MyClass<T>{ .. public void copyData(T data){ T

Deep clone utility recommendation [closed]

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问题 Is there any utility for deep cloning for java collections: Arrays Lists Maps NOTE: prefer some solution without usage of serialization, but with use of Object.clone() method. I can be sure that my custom object will implement clone() method and will use only java-standard classes that are cloneable... 回答1: I think the previous green answer was bad , why you might ask? It adds a lot of code It requires you to list all fields to be copied and do this This will not work for Lists when using

How to clone or copy a list?

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问题 What are the options to clone or copy a list in Python? While using new_list = my_list , any modifications to new_list changes my_list everytime. Why is this? 回答1: With new_list = my_list , you don't actually have two lists. The assignment just copies the reference to the list, not the actual list, so both new_list and my_list refer to the same list after the assignment. To actually copy the list, you have various possibilities: You can use the builtin list.copy() method (available since

How do you clone a BufferedImage

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问题 I have an object which has many bufferedimages in it, I want to create a new object copying all the bufferedimages into the new object, but these new images may be altered and i don\'t want the original object images to be altered by altering the new objects images. is that clear? Is this possible to do and can anyone suggest a good way to do it please? I have thought of getSubImage but read somewhere that any changes to the subimage are relected back to the parent image. I just want to be

In Java, what is a shallow copy?

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问题 java.util.Calendar.clone() returns \"...a new Calendar with the same properties\" and returns \"a shallow copy of this Calendar\". This does not appear to be a shallow copy as answered here on SO. That question is tagged language-agnostic, Java does not seem to follow the language agnostic definition. As I step through the code I notice that the structure and the elements are copied to this new object, more than the language agnostic structure only. In Java, what is a shallow copy? How does