Re: getMethod() works and works not
On 11/27/2010 10:24 AM, Alexander Burger wrote:
Mike Schilling<mscottschilling@hotmail.com> wrote:
To begin with, why is the OP using reflection at all? It's of no value in
the code actually posted, which could simply call method the normal way.
Sure, but this is just a prepared, reproducible example.
The actual code is the Java version of PicoLisp. The plain runtime
system ist at "http://software-lab.de/ersatz.tgz", the full system
including sources at "http://software-lab.de/picoLisp.tgz".
I tend to agree with Mike, nevertheless. This kind of reflection
binding is something only an author could love. Static types and strong
typing are too valuable to give up.
The only way to do this is to search the method signatures. Probably
something you could have done, but I promised help, so here it is. Note
this is a first fit algorithm, not a best fit. If there are multiple
matches for signatures (i.e., the method name is overloaded) we take the
first one that works.
package test;
import javax.swing.*;
import java.lang.reflect.*;
public class F
{
public static void main( String[] args )
throws Exception
{
JFrame frame = new JFrame( "Title" );
JPanel panel = (JPanel) frame.getContentPane();
JTextArea area = new JTextArea( 10, 40 );
frame.setSize( 300, 200 );
frame.setLocation( 200, 200 );
// This works ('add' JTextArea to JPanel):
panel.add( area );
// This, however, does not work (same 'add' JTextArea to JPanel):
//??? method = panel.getClass().getMethod("add",area.getClass());
exeMethod( panel, "add", area );
frame.setVisible( true );
}
public static Object exeMethod( Object o, String method,
Object... params )
throws NoSuchMethodException, IllegalAccessException,
IllegalArgumentException, InvocationTargetException
{
Object retVal = null;
Method[] methodList;
methodList = o.getClass().getMethods();
looking: // looking for methods
for( Method m : methodList ) {
if( m.getName().equals( method ) ) {
Class<?>[] paramTypes = m.getParameterTypes();
if( paramTypes.length == params.length ) {
for( int i = 0; i < paramTypes.length; i++ ) {
Class<?> class1 = paramTypes[i];
if( !(class1.isInstance( params[i] )) ) {
continue looking;
}
}
// all parameters check out here:
System.err.println( "Calling: " + m );
retVal = m.invoke( o, params );
}
}
}
return retVal;
}
}