Hello.
I am trying to write a processing app to send a text file line by line to an Arduino. It works, but it's sending the file so fast that it doesn't have time to do what it needs to do which is to move stepper motors. I tried to use a delay() but it is giving me this error:

"java.lang.IllegalMonitorStateException: current thread not owner

at java.lang.Object.wait(Native Method)

at processing.core.PApplet.delay(PApplet.java:2121)

at Temporary_1338_948$1.drop(Temporary_1338_948.java:56)"

Code:

import processing.serial.*;

import java.awt.dnd.*;
import java.awt.datatransfer.*;

int senddelay = 250;
PFont font;
String textDisplayed = "";

 DropTarget dt = new DropTarget(this, new DropTargetListener() {
  public void dragEnter(DropTargetDragEvent event) {
    // debug messages for diagnostics
    //System.out.println("dragEnter " + event);
    event.acceptDrag(DnDConstants.ACTION_COPY);
  }
 
  public void dragExit(DropTargetEvent event) {
    //System.out.println("dragExit " + event);
  }
 
  public void dragOver(DropTargetDragEvent event) {
    //System.out.println("dragOver " + event);
    event.acceptDrag(DnDConstants.ACTION_COPY);
  }
 
  public void dropActionChanged(DropTargetDragEvent event) {
    //System.out.println("dropActionChanged " + event);
  }
 
  public void drop(DropTargetDropEvent event) {
    //System.out.println("drop " + event);
    event.acceptDrop(DnDConstants.ACTION_COPY);
 
    Transferable transferable = event.getTransferable();
    DataFlavor flavors[] = transferable.getTransferDataFlavors();
    int successful = 0;
 
    for (int i = 0; i < flavors.length; i++) {
 try {
   Object stuff = transferable.getTransferData(flavors[i]);
   if (!(stuff instanceof java.util.List)) continue;
   java.util.List list = (java.util.List) stuff;
 
   for (int j = 0; j < list.size(); j++) {
     Object item = list.get(j);
     if (item instanceof File) {
  File file = (File) item;
 
   
  String filename = file.getPath();
  if(filename.lastIndexOf(".txt") != -1){
    String lines[] = loadStrings(filename);
    println("there are " + lines.length + " lines");

    for (int p=0; p < lines.length; p++) {
	delay(senddelay);
	String currentline = lines[p];
	println(currentline);
	send(currentline);
    }
  }
  else{
    println("wrong filetype! txt supported");
  }
     }
   }
 
 }  
 catch (Exception e) {
   e.printStackTrace();
 }
    }
  }
}
);  

 // The serial port
Serial port;				

// Serial variables
String serialString = "";

void setup() {
  size(200, 200);


   
  // SERIAL SETUP
  // Print a list of the serial ports, for debugging purposes:
  println("Serial ports");
  println(Serial.list());

  // On my computer, the Arduino is the first port
  print("Selected port: ");
  println(Serial.list()[1]);
  port = new Serial(this, Serial.list()[1], 57600);

  font = loadFont("Arial-BoldMT-48.vlw");
  textFont(font, 22); 
}

void draw() {
  background(176);  
  text(textDisplayed, 15, 60); 
}

void send(String currline) {
  textDisplayed = currline;
  port.write(currline); 
  port.write(13); 
}