Getting MethodMissingException on trying to run groovy class

[Himanshu Gupta]

Whenever I am trying to Compile the groovy class I am getting this error.

My groovy class is :

class Book {
private String title
Book (String theTitle) {
title = theTitle }

String getTitle(){
return title
}
}

and the console error is :

groovy.lang.GroovyRuntimeException: This script or class could not be run.
It should either:
- have a main method,
- be a JUnit test, TestNG test or extend GroovyTestCase,
- or implement the Runnable interface.


Please help to solve this error.

[Himanshu Gupta]

same error is coming when I am executing this functin

5.add(5)

But sometimes it does not show error.

Dont know what is happening?




[ ]

[Matthew Taylor]

I'll take the easy one first

Originally posted by Himanshu Gupta:

5.add(5)

Should be:

5.plus(5)

See the Number API.

[Himanshu Gupta]

Thanks.

Can you help me in the error in compiling class also?

[Matthew Taylor]

Originally posted by Himanshu Gupta:

class Book {
    private String title
    
    Book (String theTitle) {
        title = theTitle 
    }
 
    String getTitle(){
        return title
    }
}

This looks too much like Java code! Try something more like this:

class Book {
   String title
}
 
def book = new Book(title:'The Shining')

Specifically, there are two Groovy language features that you should take advantage of.

1. Automatic getters and setters, or Groovy Beans. No need to defined those methods, or call them. Groovy provides them for you.

2. In Groovy, there is a feature called named parameters. This allows you to pass the names of the properties you want to set into the constructor of an object. You can do this with any method, even when calling a Java api.

[Himanshu Gupta]

Sorry for troubling you again but now I am getting this error after changing the code:

Exception thrown: org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed, /C:/Documents%20and%20Settings/u17793/Desktop/groovy-binary-1.6-beta-2/groovy-1.6-beta-2/bin/Book.groovy: 1: Invalid duplicate class definition of class Book : The source /C:/Documents%20and%20Settings/u17793/Desktop/groovy-binary-1.6-beta-2/groovy-1.6-beta-2/bin/Book.groovy contains at least two defintions of the class Book.
One of the classes is a explicit generated class using the class statement, the other is a class generated from the script body based on the file name. Solutions are to change the file name or to change the class name.
@ line 1, column 1.
class Book {
^

1 error

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed, /C:/Documents%20and%20Settings/u17793/Desktop/groovy-binary-1.6-beta-2/groovy-1.6-beta-2/bin/Book.groovy: 1: Invalid duplicate class definition of class Book : The source /C:/Documents%20and%20Settings/u17793/Desktop/groovy-binary-1.6-beta-2/groovy-1.6-beta-2/bin/Book.groovy contains at least two defintions of the class Book.
One of the classes is a explicit generated class using the class statement, the other is a class generated from the script body based on the file name. Solutions are to change the file name or to change the class name.
@ line 1, column 1.
class Book {
^

1 error

[Matthew Taylor]

If you have a file called "Book.groovy" with this code:

class Book {
        String title
        String toString() {
                title
        }
}

And another file called "makeBook.groovy" with this code:

def book = new Book(title:'The Shining')
println book

And you execute this from your command line:

groovy makeBook.groovy

You should see this:

The Shining

Does that work?
[ October 15, 2008: Message edited by: Matthew Taylor ]

[Marc Peabody]

If you run your code in GroovyConsole, you don't have to put it in two separate files. Just paste the whole thing in there and hit Ctrl+Enter to run it.

It's soooooo much faster!

[Marc Peabody]

If you haven't started GroovyConsole before, just type groovyConsole in your command line. The GroovyConsole window will magically appear.

[Himanshu Gupta]

Thanks

It worked by putting all code in console and running it.


I want to learn making class file which will have methods and classes and then using it with normal Java code.