calling my PApplet object from a Java object?

Programming Questions

fearless_..

calling my PApplet object from a Java object?

in Programming Questions • 1 year ago

I'm sure this is rather fundamental, but I don't see how to call back into my PApplet object from a Java object. E.g.:

// file MyApp.pde
Pet dog;
String name;
void setup() {
dog = new Pet(this);
}
void setName(String n) {
name = n;
}
// file Pet.java
class Pet {
PApplet _parent;
public Pet(PApplet parent) {
_parent = parent;
}
public void doStuff() {
_parent.setName("fido");
}
}

My intent is to have my PApplet contain some global state, e.g. name, and to be able to modify that state from a Java class instantiated by my PApplet. But the call to _parent.setName('fido') results in processing.app.Exception: the function setName(String) does not exist.

I'm sure this is a pretty simple problem, but as I said, I don't see what the real fix is. Thanks in advance.

Replies(4)

PhiLho

Re: calling my PApplet object from a Java object?

1 year ago

class Pet {
MyApp _parent;
public Pet(MyApp parent) {
_parent = parent;
}
public void doStuff() {
_parent.setName("fido");
}
}

PApplet doesn't have setName, MyApp has it, and it is a PApplet, so you can still call all PApplet functions on it.

fearless_..

Re: calling my PApplet object from a Java object?

1 year ago

(I shouldn't post questions before my first cup of coffee...) I know that I have to subclass PApplet if it's going to have a setName method. Are you saying that the mere existence of MyApp.pde implicitly declares MyApp as a subclass of PApplet?

Awp! Never mind -- I tried it and sure enough that works. (Thank you!) Follow on question, then: where in the docs do I find the overview staying that MyApp.pde implicitly defines MyApp as a subclass of PApplet?

PhiLho

Re: calling my PApplet object from a Java object?

1 year ago

You already assumed that, since you pass this where a PApplet is required...
I don't recall exactly where it is indicated, I know that by a mix of reading doc, source code of Processing, and as you can do, just an export of the sketch: you can see in the .java file(s) how Processing pre-process the code to create a Java class, and that the name of the sketch is used to make the name of the class extending PApplet.

fearless_..

Re: calling my PApplet object from a Java object?

1 year ago

Ah! I hadn't yet done an export, so the mechanism by which Processing interfaced to Java was invisible to me. Now I know (it's by pre-processing the Processing source). Thank you for that tip.

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