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POJava: recommended solution for deep cloning/copying an instance
 

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    <p>I'm wondering if there is a recommended way of doing deep clone/copy of instance in java.</p> <p>I have 3 solutions in mind, but I can have miss some, and I'd like to have your opinion</p> <p>edit: include Bohzo propositon and refine question: it's more about deep cloning than shallow cloning.</p> <h2>Do it yourself:</h2> <p>code the clone by hand properties after properties and check that mutable instances are cloned too.<br> <strong>pro:</strong><br> - control of what will be performed<br> - quick execution<br> <strong>cons:</strong><br> - tedious to write and maintain<br> - bug prone (copy/paste failure, missing property, reassigned mutable property) </p> <h2>Use reflection:</h2> <p>With your own reflection tools or with an external helper (like jakarta common-beans) it is easy to write a generic copy method that will do the job in one line.<br> <strong>pro:</strong><br> - easy to write<br> - no maintenance<br> <strong>cons:</strong><br> - less control of what happens<br> - bug prone with mutable object if the reflection tool does not clone sub objects too<br> - slower execution</p> <h2>Use clone framework:</h2> <p>Use a framework that do it for you, like :<br> <a href="http://commons.apache.org/proper/commons-lang/javadocs/api-3.0.1/org/apache/commons/lang3/SerializationUtils.html" rel="noreferrer">commons-lang SerializationUtils</a><br> <a href="https://github.com/kostaskougios/cloning" rel="noreferrer">Java Deep Cloning Library</a><br> <a href="http://dozer.sourceforge.net/documentation/about.html" rel="noreferrer">Dozer</a><br> <a href="https://github.com/EsotericSoftware/kryo" rel="noreferrer">Kryo</a></p> <p><strong>pro:</strong><br> - same as reflection<br> - more control over what will be exactly be cloned.<br> <strong>cons:</strong><br> - every mutable instance is fully cloned, even at the end of the hierarchy<br> - could be very slow to execute</p> <h2>Use bytecode instrumentation to write clone at runtime</h2> <p><a href="http://www.jboss.org/javassist" rel="noreferrer">javassit</a>, <a href="http://jakarta.apache.org/bcel/index.html" rel="noreferrer">BCEL</a> or <a href="http://cglib.sourceforge.net/" rel="noreferrer">cglib</a> might be use to generate a dedicated cloner as fast as one hand writed. Someone knows a lib using one of these tools for this purpose ?</p> <p>What I have missed here ?<br> Which one would you recommend ?</p> <p>Thanks.</p>
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    1. COapparently Java Deep Cloning Library moved here : code.google.com/p/cloning
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