Processing 1.0 - Processing Discourse - class strucure in Eclipse

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class strucure in Eclipse (Read 893 times)

4dplane

class strucure in Eclipse
Apr 25^th, 2006, 8:18am

I am trying to move a processing program over to Eclipse and I am having some troubles with basic class structure.

Here is a test script to show the problem I am having

First:

import processing.core.*;
import processing.opengl.*;

public class test4 extends PApplet {

testTest t1;

public void setup() {

size(200, 200);

t1 = new testTest();

}

public void draw() {

background(255);

fill(120,120,0);
//t1.update();

}

}

The above script works fine but if I uncomment “t1.update()” and have this script run:

import processing.core.*;
import processing.opengl.*;

public class testTest extends PApplet {

public testTest() {

}

public void update() {

fill(120,120,0);

rect(20,20,20,20);

}

}

I get this error:

java.lang.NullPointerException

at processing.core.PApplet.fill(PApplet.java:7006)

at testTest.update(testTest.java:8)

at test4.draw(test4.java:13)

at processing.core.PApplet.handleDisplay(PApplet.java:1330)

at processing.core.PGraphics.requestDisplay(PGraphics.java:535)

at processing.core.PApplet.run(PApplet.java:1146)

at java.lang.Thread.run(Unknown Source)
Error while running applet.

All I am doing is having a different class do the drawing to screen – the above set up works in processing so why not of Eclipse?

Thanks

4dplane

watz

Re: class strucure in Eclipse
Reply #1 - Apr 25^th, 2006, 12:44pm

The reason you are getting a null pointer exception is that testTest hasn't been properly initialized as an applet. But unless you need two separate processes with two separate windows, you only need one of your classes to extend PApplet. The other (i.e. "testTest") should receive a PApplet object reference from the class that is acting as "parent".

The following will work, note the use of "this" to provide testTest with a reference to the parent PApplet object.

Code:

import processing.core.*;
import processing.opengl.*;
 
public class test4 extends PApplet {
 
testTest t1;
 
public void setup() {
  size(200, 200);
  t1 = new testTest(this); 
}
 
public void draw() {
  background(255);
  fill(120,120,0);
  t1.update();
 } 
}
 

import processing.core.*;
import processing.opengl.*;
 
public class testTest  {
 PApplet p;

 public testTest(PApplet _p) {
   p=_p;
 }
 
 public void update() {
  p.fill(120,120,0);
  p.rect(20,20,20,20);
 }
}

marius watz // unlekker // code & form // Generator.x

4dplane YaBB Newbies Offline Posts: 45	Re: class strucure in Eclipse Reply #2 - Apr 25^th, 2006, 6:30pm Ahh! - what would I do without people like you? Thanks for the input, 4dplane sidenote - above you posted my code in proper format, what <><> command does this?

JohnG Ex Member	Re: class strucure in Eclipse Reply #3 - Apr 25^th, 2006, 6:54pm It's {code} {/code} except with square brackets []

bladamir YaBB Newbies Offline Posts: 5 CA	Re: class strucure in Eclipse Reply #4 - Mar 28^th, 2008, 5:44am thank you for being so intelligent. I had a similar mindcrappity smack going on.
	-blad

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