Re: getMethod() works and works not

On 11/27/2010 10:24 AM, Alexander Burger wrote:


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;
    }
}