Implementing a password field

import controlP5.*;

void setup(){
 size(480,640);
 ControlP5 id=new ControlP5(this);
 ControlP5 pw=new ControlP5(this);

 PFont font=createFont("arial", 20);

 //id input
 id.addTextfield("ID", 180,300,200,50)
   .setFont(font);

 pw.addTextfield("PASSWORD", 180,400,200,50);
 pw.setFont(font);
}

void draw(){
  background(0);
}

I made two textfields so that I can receive two inputs, one for ID and one for password. What I want to do is to cover password with '*'. How can I do it?

I want to cover password with *