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POIs there any way to modify the value of a `private static final` field in Java from outside the class?
 

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  1. POIs there any way to modify the value of a `private static final` field in Java from outside the class?
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    <p>I know this is normally rather stupid, but don't shoot me before reading the question. I promise I have a good reason for needing to do this :)</p> <p>It's possible to modify regular private fields in java using reflection, however Java throws a security exception when trying to do the same for <code>final</code> fields.</p> <p>I'd assume this is strictly enforced, but figured I'd ask anyway just in case someone had figured out a hack to do this. </p> <p>Let's just say I have an external library with a class "<code>SomeClass</code>"</p> <pre><code>public class SomeClass { private static final SomeClass INSTANCE = new SomeClass() public static SomeClass getInstance(){ return INSTANCE; } public Object doSomething(){ // Do some stuff here } } </code></pre> <p>I essentially want to Monkey-Patch SomeClass so that I can execute my own version of <code>doSomething()</code>. Since there isn't (to my knowledge) any way to really do that in java, my only solution here is to alter the value of <code>INSTANCE</code> so it returns my version of the class with the modified method.</p> <p>Essentially I just want to wrap the call with a security check and then call the original method. </p> <p>The external library always uses <code>getInstance()</code> to get an instance of this class (i.e. it's a singleton).</p> <p>EDIT: Just to clarify, <code>getInstance()</code> is called by the external library, not my code, so just subclassing won't solve the issue. </p> <p>If I can't do that the only other solution I can think of is to copy-paste entire class and modify the method. This isn't ideal as I'll have to keep my fork up to date with changes to the library. If someone has something a little more maintainable I'm open to suggestions. </p>
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    1. USJames Davies
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    1. COToo bad there aren't any extension methods in Java
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      1. USJon Limjap
    2. COYou need python :P
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      1. USRexsung
    3. COI took the liberty to add "static" to getInstance(), as that's probably how it looks like.
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      1. USJoachim Sauer
 

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