Tom Igoe submitted these changes to improve the behavior of the program:

p69, second >> box (text and facing code):

1) Delete the paragraph beginning with "Add a loop..." and ending with "three sensor readings."
2) Delete the facing code ("while (Serial.available"...)
3) Move the paragraph "Next, add some..." to the box above so it appears after the paragraph ending "...like this:"
4) This >> box should now be empty. Delete it.

p69, first >> box (text):

1) Change "To make this happen, first" to "Next,"

p69, add a new >> box at the top of the page (text and facing code):

1) Text: "To make this happen, first add the following lines to the startup() of the Arduino program. This makes the Arduino send out a serial message until it gets a response from Processing:"
2) Code:
while (Serial.available() <= 0) {
Serial.println("hello"); // send a starting message
delay(300);
}

p69, last >> box (code)
1) Delete only the following lines:
// if serialEvent occurs at all, contact with the microcontroller
// has been made:
if (madeContact == false) {
myPort.clear(); // clear the serial port buffer
madeContact = true;
myPort.write('\r');
}
2) Add the following line after the third line in this listing:
myString = trim(myString);
3) After the line reading "if (myString != null) {", replace "myString = trim(myString);" with the following:
// if you haven't heard from the microcontroller yet, listen:
if ( madeContact == false) {
if (myString.equals("hello")) {
myPort.clear(); // clear the serial port buffer
madeContact = true; // you've made contact with the microcontroller
myPort.write('\r'); // ask for more
}
}

4) If the correct lines have been deleted/added, these will be the first 15 lines in the program:
void serialEvent(Serial myPort) {
// read the serial buffer:
String myString = myPort.readStringUntil(linefeed);
myString = trim(myString);

// if you got any bytes other than the linefeed:
if (myString != null) {
// if you haven't heard from the microcontroller yet, listen:
if ( madeContact == false) {
if (myString.equals("hello")) {
myPort.clear(); // clear the serial port buffer
madeContact = true; // you've made contact with the microcontroller
myPort.write('\r'); // ask for more
}
}