We can have two public classes in one java file

9. How many classes can be defined in a single program? Explanation: Any number of classes can be defined inside a program, provided that their names are different.

Every Java program requires the presence of at least one class .

We can create as many classes as we want but writing many classes in a single file is not recommended as it makes code difficult to read rather we can create a single file for every class.12 Haz 2019

I would say more than 10,000 classes is a lot. This is more than the entire JDK. Keep in mind that often you’ll want to use a common superclass with several subclasses, with most of the logic in the superclass and only the stuff that’s necessarily different in the subclasses.