[Pattern] Class.newInstance() to constructor reflection

[brunoborges]

Category

tooling

Slug

class-newinstance-to-constructor

Title

Class.newInstance() to constructor reflection

Difficulty

intermediate

Since JDK

9

Summary

Replace deprecated Class.newInstance() with explicit constructor lookup and invocation.

Old code label

Deprecated Class.newInstance()

Old code

Plugin plugin = pluginClass.newInstance();

Modern code label

Constructor reflection

Modern code

Plugin plugin = pluginClass
        .getDeclaredConstructor()
        .newInstance();

Explanation

Class.newInstance() is deprecated because it can bypass compile-time checking for exceptions thrown by the constructor and only supports a zero-argument constructor. Explicit Constructor lookup makes the selected signature visible and reports reflective invocation failures through the appropriate reflection exceptions. Module and access rules still apply; this pattern does not recommend bypassing encapsulation.

Why the modern way wins

✅ Supported API — Removes use of deprecated Class.newInstance().
🎯 Explicit constructor — The requested signature is visible and can accept arguments.
🛡 Honest failures — Constructor exceptions are represented through InvocationTargetException.