invokeMethod from Groovy with no parameters

Question

Dear All:

I have some Java code that seemed to work fine:

/**
 * Helper method
 * 1. Specify args as Object[] for convenience
 * 2. No error if method not implemented 
 * (GOAL: Groovy scripts as simple as possible)
 * 
 * @param name
 * @param args
 * @return
 */
Object invokeGroovyScriptMethod(String name, Object[] args) {
    Object result = null;
    try {
        result = groovyObject.invokeMethod(name, args);         
    } catch (exception) { // THIS HAS BEEN GROVIED...
        if (exception instanceof MissingMethodException) {
            if (log.isDebugEnabled()) {
                log.debug("invokeGroovyScriptMethod: ", exception);
            }
        } else {
            rethrow exception;
        }
    }
    return result;
}

Object invokeGroovyScriptMethod(String name) {
    return invokeGroovyScriptMethod(name, [ null ] as Object[]);
}

Object invokeGroovyScriptMethod(String name, Object arg0) {
    return invokeGroovyScriptMethod(name, [ arg0 ] as Object[]);
}

Object invokeGroovyScriptMethod(String name, Object arg0, Object arg1) {
    return invokeGroovyScriptMethod(name, [ arg0, arg1 ] as Object[]);
}

but I am having problems with the method:

Object invokeGroovyScriptMethod(String name) {
    return invokeGroovyScriptMethod(name, [ null ] as Object[]);
}


groovy.lang.MissingMethodException: No signature of method: MyClass.getDescription() is   applicable for argument types: (null) values: [null]
Possible solutions: getDescription(), setDescription(java.lang.Object)

Any hints?

Thank you Misha

Answer 1

I had a quick go (getting rid of the log bit and replacing it with a println as I didn't have the logs set up in my tests), and I came up with this that doesn't require the overloaded versions of invokeGroovyScriptMethod:

Object invokeGroovyScriptMethod( String name, Object... args = null ) {
  try {
    args ? groovyObject."$name"( args.flatten() ) : groovyObject."$name"()
  } catch( exception ) {
    if( exception instanceof MissingMethodException ) {
      println "invokeGroovyScriptMethod: $exception.message"
    } else {
      throw exception;
    }
  }
}

groovyObject = 'hi'
assert    'HI' == invokeGroovyScriptMethod( 'toUpperCase' )
assert     'i' == invokeGroovyScriptMethod( 'getAt', 1 )
assert '***hi' == invokeGroovyScriptMethod( 'padLeft', 5, '*' )

// Assert will pass (as we catch the exception, print the error and return null)
assert    null == invokeGroovyScriptMethod( 'shouldFail' )

---

edit

Just read the question again, and you say this is a Java class? But then the catch seems to point to this being Groovy code...

I fear I may have sent you down the wrong path if this is Java...