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POWhen does it make sense for a Java object to be Serializable but not Cloneable?
 

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  1. POWhen does it make sense for a Java object to be Serializable but not Cloneable?
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    <p>If a Java class implements the <code>Serializable</code> interface but does not have a public <code>clone()</code> method, it is usually possible to create a deep copy like this:</p> <pre><code>class CloneHelper { @SuppressWarnings("unchecked") public static &lt;T extends Serializable&gt; T clone(T obj) { try { ByteArrayOutputStream baos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(baos); oos.writeObject(obj); oos.close(); byte[] bytes = baos.toByteArray(); ByteArrayInputStream bais = new ByteArrayInputStream(bytes); ObjectInputStream ois = new ObjectInputStream(bais); T copy = (T) ois.readObject(); ois.close(); return copy; } catch (ClassNotFoundException ex) { // Shouldn't happen throw new Error(ex); } catch (IOException ex) { // Probably a bug in T's custom serialization methods throw new RuntimeException(ex); } } } </code></pre> <p>I often encounter third-party library classes like this and resort to hacks like the one above. I've even extended <code>ObjectOutputStream</code> on occasion to make the copy shallower. It's never caused serious problems, other than being inefficient (slow to encode/decode and the temporary serialization graphs can consume a lot of memory.)</p> <p>And if it is not safe to use this technique, the class probably should not have been declared <code>Serializable</code>.</p> <p>So what I would like to know is, if your class is <code>Serializable</code>, what might prevent you from defining a public <code>clone()</code> method (using either the <code>Cloneable</code> interface or a copy constructor?)</p> <hr> <p>Related: <a href="https://stackoverflow.com/questions/475842/copy-an-object-in-java">Copy an object in Java</a></p>
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      1. POWhen does it make sense for a Java object to be Serializable but not Cloneable?
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      1. POWhen does it make sense for a Java object to be Serializable but not Cloneable?
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    1. COThe question title sounds strangely like a geek joke. "When does it make sense for a Java object to be Serializable but not Cloneable?" I won't even attempt to write a punchline.
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      1. USDan Rosenstark
 

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