This reference is for Processing 3.0+. If you have a previous version, use the reference included with your software in the Help menu. If you see any errors or have suggestions, please let us know. If you prefer a more technical reference, visit the Processing Core Javadoc and Libraries Javadoc.



PrintWriter output;

void setup() {
  // Create a new file in the sketch directory
  output = createWriter("positions.txt"); 

void draw() {
  point(mouseX, mouseY);
  output.println(mouseX);  // Write the coordinate to the file

void keyPressed() {
  output.flush();  // Writes the remaining data to the file
  output.close();  // Finishes the file
  exit();  // Stops the program

Description Allows characters to print to a text-output stream. A new PrintWriter object is created with the createWriter() function. For the file to be made correctly, it should be flushed and must be closed with its flush() and close() methods (see above example).
print() Adds data to the stream
println() Adds data to the stream and starts a new line
flush() Flushes the stream
close() Closes the stream
Updated on January 1, 2021 03:38:12am EST