Hi Eric,
On Jan 16, 2008, at 11:18 PM, Eric Willigers wrote:
> John Tyler wrote:
>> Hello, I'm trying to verify some behavior I've seen. I defined a
>> file MyApp.scala as such:
>> class MyApp {
>> // blah
>> }
>> object MyApp {
>> def main(args: Array[String]) {
>> val app = new MyApp
>> // blah
>> }
>> }
>> I then compiled with "scalac MyApp.scala", but when I run with
>> "scala MyApp" from the same directory I get:
>> java.lang.NoSuchMethodException: MyApp.main([Ljava.lang.String ;)
>
>
> You might choose to explicitly declare that def main returns type Unit
>
> But the problem you are hitting is that you have both a class MyApp
> and an object MyApp. main won't work in such cases. Rename the class
> MyApp and you'll be fine. You'll see that object MyApp compiles to
> MyApp.class and MyApp$.class while class MyApp also compiles to
> MyApp.class - a collision. Class MyApp dominates instead of there
> being a merge (which might be hard with incremental compiling,
> separate compiling, etc).
>
In which case I need to update the book because it is wrong. It should
say that any *standalone object* with a main of the proper signature
can be used as an entry point into an application. MyApp$ has a main
method, but it isn't static. I had never attempted to make an
application with anything other than a standalone object.
Bill
