This file a PrintWriter object to write data continuously to a file while the mouse is pressed. When a key is pressed, the file closes itself and the program is stopped. This example won't work in a web browser because of Java security restrictions.
Original Processing.org Example: SaveFile2
// All Examples Written by Casey Reas and Ben Fry // unless otherwise stated. PrintWriter output; void setup() { size(200, 200); // Create a new file in the sketch directory output = createWriter("positions.txt"); frameRate(12); } void draw() { if (mousePressed) { point(mouseX, mouseY); // Write the coordinate to a file with a // "\t" (TAB character) between each entry output.println(mouseX + "\t" + mouseY); } } void keyPressed() { // Press a key to save the data output.flush(); // Write the remaining data output.close(); // Finish the file exit(); // Stop the program }