If random() is the only PApplet non-static member you need, you can replace it w/ Math.random(): 
Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Math.html#random()
Or even Java’s Random class for more flexibility: 
Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/util/Random.html