Why a Single Java Source File Can Not Have More Than One Public Class

Question

https://dzone.com/articles/why-single-java-source-file-can-not-have-more-than..
I CANT UNDERSTAND EASILY

Answer 1

most of the answers I found are giving reason "to improve code readability & to organice code"
//btw U will some examples too :
https://stackoverflow.com/questions/3578490/why-only-1-public-class-in-java-file

Answer 2

i read it..
but..
cant put my finger.