I’m programming a game for a programming course in college, and I’ve run into some trouble with the .getConstructor method. What I’m trying to do is pass a class that has to be a subclass of another class as an argument into a method and create a new instance of that class there to do some other stu…

[image] PeterAmbos: Ingredient ingredient = ingredientClass.getDeclaredConstructor(sketchClass).newInstance(this); That got me an IllegalArgumentException: argument type mismatch, Java’s keyword this represents the current class’ code block type. Your newInstance(this) expects you to pass a…

[image] PeterAmbos: ice_creamillionaire m missing here :wink: Chrisir

[image] java.lang.NoSuchMethodException from a Class.forName instantiation Coding Questions The 3 classes (Dumb, Dumber, Dummy) in my example are both non-static & non-public. So it’s very possible to find such classes as my example already demonstrates. I’ve split up g…

I have a class // =========================================================== // That's the basic class for all elements abstract class ElectricElement { .... Then I have a few classes such as // ========================================================= class Motor extends ElectricElement { …

Processing wraps your sketch code inside a class named after the sketch so all your classes are inner classes. To instantiate an inner class using reflection requires an instance of the enclosing class. The easiest solution is to make all your classes top-level by declaring them public static but i…

Thank you for linking me to those two topics - I’ve read them carefully and with some more research, I understood why I have to use .getDeclaredConstructor and give it the sketch’s class as an argument. So now, following your implementation from this topic: How do you choose what class you add to a…

Thanks, that sounds like a good solution, but when I’ve tried working with static classes and methods in the past (and also just now when I tried it out again), the IDE always complains that I can’t access inbuilt Processing functions in those classes and methods any more, as the methods from PApple…

OK the version below works with inner classes so should solve the creation problem and access to Processing methods. import java.lang.reflect.*; import java.util.*; GameCharacter player; public void setup() { size(400, 300); player = new PlayerCharacter(); player.addToInventory(this, Vanill…

Thanks so much, that solved it. I now also added final PApplet sketch = this; to the top and changed the method code to Ingredient ingredient = ingredientClass.getDeclaredConstructor(sketchClass).newInstance(sketch); and finally it works! Thanks a lot to you too @quark , you already got me on the…

Although reflection/introspection is a powerful workaround tool, we should avoid abusing it. You could easily replace newInstance() w/ a switch / case block, where each “className” has a corresponding return new className();.

Why does .getConstructor fail with a NoSuchMethodException despite zero-arg constructors existing for the class?

Processing Coding Questions

GoToLoop February 12, 2025, 4:33pm 3

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Why does .getConstructor fail with a NoSuchMethodException despite zero-arg constructors existing for the class?

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