Is possible set. Public static void sayhello()?

Answer 1

You don't need to set it public.
Public means other classes have access.
Hope this example helps you:

https://code.sololearn.com/cBQmUDJb9N3h/?ref=app

Answer 2

Can you explain what you mean?
Do you mean this?

public static void sayHello(String name){

System.out.println("Hello " + name);
}

sayHello("David");
//Output: "Hello David"

Answer 3

Well i need set public or not?

Answer 4

Oooo okay
So don't matter that method is private when that class is public?