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Index › Programming Questions & Help › Electronics,  Serial Library › serial in applet not working
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serial in applet not working (Read 1516 times)
mac
serial in applet not working
Nov 26th, 2008, 3:26pm  
Hello, I just installed today the processing to test the serial port access. It works in Processing, the exe for Windows also, the applet is not starting. The error is:
--------------------------------------------------------
Exception in thread "Animation Thread" java.lang.NoClassDefFoundError
at processing.serial.Serial.<init>(Serial.java:128)
at processing.serial.Serial.<init>(Serial.java:102)
at serial_read.setup(serial_read.java:42)
at processing.core.PApplet.handleDraw(PApplet.java:1383)
at processing.core.PApplet.run(PApplet.java:1311)
at java.lang.Thread.run(Unknown Source)
----------------------------------------------------------

I have installed the JRE-Version 1.5.0_15

Here is the code:

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
import processing.core.*;
import processing.serial.*;


Serial myPort;  // Create object from Serial class
String myString = null;
PFont fontA;


void setup()
{
 size(400, 400);
 background(255,255,255);
 myPort=new Serial(this,"COM2",9600);
 myPort.clear();
 myString = myPort.readStringUntil(10);
 myString = null;
 
 fontA = loadFont("ArialNarrow-48.vlw");
 textFont(fontA, 25);
}

void draw() {
 
 while (myPort.available() > 0) {
   myString = myPort.readStringUntil(10);
   if (myString != null) {
      background(255,255,255);
      fill(0);
      text("COM2 >> " + myString,30,30);
   }
 }
}
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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fjen
Re: serial in applet not working
Reply #1 - Nov 27th, 2008, 10:10am  
normal applets are not allowed to do serial communication (and many other possibly harmfull things), think viewing an applet on a website and it's reading your serial ports ..

the only way to do it is signing your applet, that opens a message asking the user to trust your applet to use the serial port.

http://processing.org/hacks/hacks:signapplet
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mac
Re: serial in applet not working
Reply #2 - Nov 27th, 2008, 1:13pm  
Hello fjen,
thank you for your sugestion. I have signed the applet, after opening it in IE the message was shown (about the signature) but the same error comes in the console.
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fjen
Re: serial in applet not working
Reply #3 - Nov 27th, 2008, 1:55pm  
well to be honest i never tried to do serial in an applet before. what exactly are you trying to do?

F
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mac
Re: serial in applet not working
Reply #4 - Nov 27th, 2008, 2:34pm  
I want to read/write to the serial port from a java applet communicating whith some µC.
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fjen
Re: serial in applet not working
Reply #5 - Nov 27th, 2008, 7:29pm  
that was the part is was able to guess, why do you need it to be an applet if it anyways is only going to run on the _one_ computer that has that certain microcontroller attached?

F
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mac
Re: serial in applet not working
Reply #6 - Nov 28th, 2008, 8:41am  
Good morning fjen,
You are right, there are other ways also to communicate with serial devices, I was only curious to test what I can do with Java (or not).
Anyway thank you for your interest.
mac
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