Databases
StackOverflow2013
Postsdbo
POclone() vs copy constructor vs factory method?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POclone() vs copy constructor vs factory method?
    primarykey
    data
    text
    <p>I did a quick google on implementing clone() in Java and found: <a href="http://www.javapractices.com/topic/TopicAction.do?Id=71" rel="noreferrer">http://www.javapractices.com/topic/TopicAction.do?Id=71</a></p> <p>It has the following comment:</p> <blockquote> <p>copy constructors and static factory methods provide an alternative to clone, and are much easier to implement.</p> </blockquote> <p>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.</p> <p>Here are the issues that I've noticed:</p> <h2>Copy constructors don't work with Generics.</h2> <p>Here's some pseudo-code that won't compile.</p> <pre><code>public class MyClass&lt;T&gt;{ .. public void copyData(T data){ T copy=new T(data);//This isn't going to work. } .. } </code></pre> <p>Sample 1: Using a copy constructor in a generic class.</p> <h2>Factory methods don't have standard names.</h2> <p>It's quite nice to have an interface for reusable code.</p> <pre><code>public class MyClass&lt;T&gt;{ .. public void copyData(T data){ T copy=data.clone();//Throws an exception if the input was not cloneable } .. } </code></pre> <p>Sample 2: Using clone() in a generic class.</p> <p>I noticed that clone is not a static method, but wouldn't it still be necessary to make deep copies of all the protected fields? When implementing clone(), the extra effort to throw exceptions in non-cloneable subclasses seems trivial to me.</p> <p>Am I missing something? Any insights would be appreciated.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USakarnokd
    1. USUser1
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    3. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POclone() vs copy constructor vs factory method?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POclone() vs copy constructor vs factory method?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POclone() vs copy constructor vs factory method?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COSee also http://stackoverflow.com/questions/1086929/if-you-dont-clone-in-java-then-what-do-you-do-and-what-do-you-call-it
      singulars
      1. POclone() vs copy constructor vs factory method?
      1. USfinnw
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload