The following text was written to the standard output stream when the ShapesThing.java program was executed from IntelliJ.
square =< Square: side=400.0> area of square = 160000.0 perimeter of square =1600.0 diagonal of square = 565.685424949238 disk =< Circle: radius=200.0> area of disk =125663.70614359173 perimeter of disk =1256.6370614359173 diamond = < Square: side=282.842712474619>