import java.awt.*;

TextField textField = new TextField("type here", 16);
color bg = color(33,33,33,255);

void setup(){
 size(200,200);
 add(textField);
}

void draw(){
 background(bg);
}

Sorry to be a pest...
Unless I missed a post stating otherwise, Fry addressed this point a few months back; here's the essential quote:
" processing code is preprocessed into java, so most things just work.. the exception is generally anything using java.awt.* or java.swing.*, which should be avoided."

I had a student this year who attempted to code a textField of sorts in Processing. Although her focus was more on self-expression than developing anything "useful"; it was a good academic exercise. It's probably best to let Processing be what it was designed to be-a wonderfully user-friendly graphics component.

I assume you know Java, so you might try building a Swing app and sticking your TextField and PApplet in a JFrame layout, as separate components.

Fry says:
"...an applet is just a component and you can add it to a swing layout the way you would any other awt component. as of recent releases, PApplet handles resizing itself properly when the layout manager asks it to.

noLoop() and redraw() are important in these situations, so that you don't have several animation threads running that need not be, and so that they aren't fighting with each other.
"

There's more info scattered around the board about this topic.