how to initialize PApplet

Android Processing

wzb.zju

in Android Processing • 2 years ago

I want to use methods in PApplet, but do not want to create a class extending PApplet.

Here is my code:

public class TestMain {

public static void main(String args[]){

PApplet pa = new PApplet();

pa.size(200,200);

}

An error happends for the line pa.size(200,200) .

Exception in thread "main" java.lang.NullPointerException
at processing.core.PApplet.size(Unknown Source)
at processing.core.PApplet.size(Unknown Source)

I think it maybe because the initialization of PApplet is not correct, but I do not know to solve it.

Does anyone know how to solve it? Thanks!

Replies(10)

PhiLho

Disclaimer: I know nothing about Android. And I still haven't tried to run sketches outside of the PDE.
But in regular PApplet, you need to first call PApplet.main() with some arguments to properly set up the class.
And maybe you still need to have a secondary class extending PApplet to instantiate it, so that it overrides setup(), draw() and other event handlers.

wzb.zju

Re: Re: how to initialize PApplet

2 years ago

I just tried to change the line pa.size(200,200) to pa.main(new String[] {"My sketch"}) to see what would happen. I got the following errors:

Exception in thread "main" java.lang.RuntimeException: java.lang.ClassNotFoundException: My sketch

at processing.core.PApplet.runSketch(Unknown Source)

at processing.core.PApplet.main(Unknown Source)

at TestMain.main(TestMain.java:7)

Caused by: java.lang.ClassNotFoundException: My sketch

at java.net.URLClassLoader$1.run(Unknown Source)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

... 3 more

PhiLho

Re: how to initialize PApplet

2 years ago

Well, replace My sketch with the name of your class... ie., apparently, "TestMain".

wzb.zju

Re: Re: how to initialize PApplet

2 years ago

I changed it to pa.main(new String[] {"TestMain"}); but I got another error

Exception in thread "main" java.lang.RuntimeException: java.lang.ClassCastException: TestMain cannot be cast to processing.core.PApplet

at processing.core.PApplet.runSketch(Unknown Source)

at processing.core.PApplet.main(Unknown Source)

at TestMain.main(TestMain.java:7)

Caused by: java.lang.ClassCastException: TestMain cannot be cast to processing.core.PApplet

... 3 more

PhiLho

Re: how to initialize PApplet

2 years ago

Mmm, back to square one...
As I wrote, you probably need to make one class extending PApplet anyway, otherwise you won't do much drawing... Or not animated, at least. So, if you call your applet SomeApplet, you replace PApplet pa = new PApplet(); with PApplet pa = new SomeApplet(); and then pass "SomeApplet" to main().

wzb.zju

Re: Re: how to initialize PApplet

2 years ago

I did as you said:

First extend PApplet:

public class TestProcess extends PApplet {

public void setup(){

size(100,100);

background(0);

}

Then use it in main function:

public class TestMain {

public static void main(String args[]){

PApplet pa = new TestProcess();

System.out.println(pa.height);

}

But the output of height is still 0. I guess it is still not animated correctly.

Do you know why? Thanks!

PhiLho

Re: how to initialize PApplet

2 years ago

I would try (still hypothetically...):

public class TestMain {

public static void main(String args[]){

PApplet pa = new TestProcess();

pa.main(new String[] { "TestProcess" });

System.out.println(pa.height);

}

wzb.zju

Re: Re: how to initialize PApplet

2 years ago

After I adding that line, a new window come out. But the height value is still 0.

PhiLho

Re: how to initialize PApplet

2 years ago

Add a println() in setup(), after size(), to see which one is printed first...

wzb.zju

Re: Re: how to initialize PApplet

2 years ago

The value in setup is printed first and it is 100. But the height value in main is still 0.

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