Well, why are you using a text file for such task? Isn't it simpler to just keep the data in memory? Applets have trouble to access files on the user's computer, for security reasons, so if you really want to do it this way, you have to sign your applet.

The way I thought it would work would be that the data file would be in the same location on the webserver as the html file and processing sketch, and the sketch would just modify it every time the applet is run. What do you mean by keeping the data in memory? I hope there's a more efficient way than I've found.

If I have time, I will try and take a look at your sketch and see if you can get rid of the text, but I dislike having to dig into zip files to see code (although they are useful to test a code with assets).

To save a file on the server, you have to send a POST request to upload the file. Or, for simple, short texts, a simple GET request (passing the encoded text on the param part of the URL) can be enough.

Apparently, your code can be simplified to:

1. import controlP5.*;
2. ControlP5 controlP5;
3. ControlFont font;
4. String textValue = "";
5. Textarea myTextarea;
6. Textfield myTextfield;.
7. 
   
8. String line = "Some text";
9. 
   
10. void setup() {
11.   size(800,500);
12.   frameRate(25);
13.  
14.   controlP5 = new ControlP5(this); 
15.  
16.   PFont pfont = createFont("Times",20,true); // use true/false for smooth/no-smooth
17.   font = new ControlFont(pfont);
18.  
19.   myTextarea = controlP5.addTextarea("label1", priorMessage1, 100,100,width-200,60);
20.   myTextfield = controlP5.addTextfield("reply",100,height-100,width-width/4,20);
21.   myTextfield.keepFocus(true);
22. }
23. 
    
24. void draw() {
25.   background(0);
26. }
27. 
    
28. void controlEvent(ControlEvent theEvent) {
29.  
30. }
31. 
    
32. public void reply(String theText) {
33.   // receiving text from controller texting
34.   println(theText);
35.   myTextarea.setText(theText);
36.   line = theText;
37. }

The caveat being that when you restart the applet, you loose the last message typed. If that's essential for you, you need a script on the server side to receive the text and save it to a file (and send it back when requested).

 

The caveat being that when you restart the applet, you loose the last message typed. If that's essential for you, you need a script on the server side to receive the text and save it to a file (and send it back when requested).

Yeah that's exactly what I need to do. The text the user is supposed to reply to must be saved server-side and recalled upon starting the sketch. Is there any way to do that in processing?

Is there any alternative way to achieve what I need to achieve purely with processing? I've hit a wall with this and am not sure I can continue my project in Processing otherwise.

If you want persistence of data of an applet, common to several independent locations, you need to save on a server, thus to have server side code. No alternative to that, whatever the language / platform, Processing isn't the limitation here.