Hi,
I'm using the text command, and i am getting NullPointerException fromn the complier, what does this mean? The code is not working so i guess its not good!

Thanks

Pete

Hi Cedric,
Again thanks for your support.
here is the code, its a little all over the place as its in development!
I'm trying to read in a string from the serial port and then print it out in draw(), the string is printing out ok, i just cant get the text command to work!

Thanks

Pete

Code:

//Processing code to run with this example:

import processing.serial.*;     // import the Processing serial library
Serial myPort;			// The serial port

float bgcolor;			// Background color
String fgcolor;			// Fill color
String xpos, ypos;		  // Starting position of the ball
char sender = 'A';
PFont font;
String s;
String mystring_ext;

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

  // List all the available serial ports
  println(Serial.list());

  // I know that the first port in the serial list on my mac
  // is always my  Arduino module, so I open Serial.list()[0].
  // Change the 0 to the appropriate number of the serial port
  // that your microcontroller is attached to.
  myPort = new Serial(this, Serial.list()[1], 9600);

  // read bytes into a buffer until you get a linefeed (ASCII 10):
  myPort.bufferUntil('\n');
  
  // draw with smooth edges:
  smooth();
}

void draw() {
  background(0);
  fill(150);
  font = loadFont("Aharoni-Bold-20.vlw"); 
  textFont(font); 
  background (0);
  //text("xpos", 10, 20); 
  //text("ypos", 10, 40);
  //text("fgcolor", 10, 60);  
  String s = "The quick brown fox jumped over the lazy dog.";
  text(mystring_ext, 0, 0, 200, 200);
  fill(0, 102, 153);
}

// serialEvent  method is run automatically by the Processing applet
// whenever the buffer reaches the  byte value set in the bufferUntil() 
// method in the setup():

void serialEvent(Serial myPort) { 
  // read the serial buffer:
  String myString = myPort.readStringUntil('\n');
  // if you got any bytes other than the linefeed:
    myString = trim(myString);
    mystring_ext = myString;

    // split the string at the commas
    // and convert the sections into integers:
    String sensors[] = (split(myString, ','));

    // print out the values you got:
    for (int sensorNum = 0; sensorNum < sensors.length; sensorNum++) {
	print(sensors[sensorNum] + "  "); 
    }
    // add a linefeed after all the sensor values are printed:
    println();
    if (sensors.length > 1) {
	xpos = sensors[0];
	ypos = sensors[1];
	fgcolor = sensors[2];
    }
    
    // send a byte to ask for more data:
    if (sender == 'A'){
    sender = 'B';}
    else{
    sender = 'A';}
    myPort.write(sender);
  }


 

To answer the base question: this is a runtime exception, not a compiler error.
This exception happens when you try to use an object which is not initialized: by default, it is null (if declared globally or at class level). Thus, you get this error when you try to use this non-existent object to get a field or call a method.
That's a very common error...