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    <blockquote> <p>But, what are the downsides to favouring immutable objects in Java? incompatibility with ORM or web presentation tools?</p> </blockquote> <p>Reflection based frameworks are complicated by immutable objects since they <strong>requires</strong> constructor injection: </p> <ul> <li>there are no default arguments in Java, which forces us to ALWAYS provide all of the necessary dependencies </li> <li>constructor overriding can be messy</li> <li>constructor argument names are not usually available through reflection, which forces us to depend on argument order for dependency resolution</li> </ul> <blockquote> <p>Implementation complexities?</p> </blockquote> <p>Creating immutable objects is still a boring task; the compiler should take care of the implementation details, as in <a href="http://groovy.codehaus.org/Immutable+AST+Macro" rel="nofollow noreferrer">groovy</a></p> <blockquote> <p>Is it possible to design a large-scale system (deep object graph) that predominately uses immutable objects?</p> </blockquote> <p>definitely yes; immutable objects makes great building blocks for other objects (they favor composition) since it's much easier to maintain the invariant of a complex object when you can rely on its immutable components. The only true downside to me is about creating many temporary objects (e.g. <a href="https://web.archive.org/web/20080324114426/http://java.sun.com/developer/JDCTechTips/2002/tt0305.html" rel="nofollow noreferrer">String concat was a problem in the past</a>). </p>
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    1. COUsing the Builder pattern is one way of making the construction of immutable objects safer and simpler. Maintaining Builders can be a pain without generated code however.
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      1. USPeter Lawrey
    2. COThere are workarounds for the lack of argument names with Java's reflection API. Paranamer (http://paranamer.codehaus.org/) is a pretty good library that hacks around the issue.
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      1. USRafael de F. Ferreira
    3. CO@dfa I had similar parameter problems while developing my immutable ORM: [**JIRM**](https://github.com/agentgt/jirm). I also had to combat the immutable object constructor overriding problem by generally always using static factories methods. There are still some annoying things like Spring where you do not have all the properties set on construction. For that I had to rely on Guava's Suppliers so that the fields would be final (arguable the object is not immutable) but it is threadsafe.
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      1. USAdam Gent
 

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