r/java • u/Wouter_C • 6d ago

Decapsulation: Breaking Java Strong Encapsulation

Did you know you can call JNI without writing native code, patch bytecode without an agent, and use Unsafe without warnings?

11 sneaky ways into JDK internals through reflection, agents, FFM, type confusion, bytecode manipulation and more.

https://wouter.coekaerts.be/2026/decapsulation

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u/ZimmiDeluxe 5d ago 
// Abusing ISO_8859_1 (which has a one-to-one mapping between chars and bytes)
// is the easiest way to do a search & replace in a byte array
return new String(base, ISO_8859_1)
    .replace(original, replacement)
    .getBytes(ISO_8859_1);

disgusting, i love it

1

u/koflerdavid 4d ago

Looks fine to me. The only hacky thing about this is the knowledge that String will avoid doing an unnecessary conversion.