Re: Simple question about Java Methods

From:
ram@zedat.fu-berlin.de (Stefan Ram)
Newsgroups:
comp.lang.java.programmer
Date:
18 Aug 2008 20:40:44 GMT
Message-ID:
<function-object-20080818223604@ram.dialup.fu-berlin.de>
Danger_Duck <ganggang3ster@gmail.com> writes:

org.eclipse.swt.widgets.Combo.Combo [...]
Based on the selection, I want to create a different function.


  I don't know org.eclipse, but you can create function objects

interface Function { public double valueAt( final double x ); }

class Sin implements Function
{ public double valueAt( final double x )
  { return java.lang.Math.sin( x ); }}

....

final Function sin = new Sin();

....

  And then you can store the object ?sin? in the combo box
  field, so that it is returned upon selection - if org.eclipse
  supports this.

  So there will be no need to ?create? anything, the function
  object can be used directly as sent by the field, possibly
  after a downcast from ?Object? to ?Function?.
                             ~~

  It is a big shame than Java SE does not define common interfaces
  such as ?Function<S,T>?. This would increase interoperability
  between source code from different sources as they could then
  all share these interfaces. Nowadays, unfortunately, everyone
  is still forced to define his own interface. For example,

http://www.purl.org/stefan_ram/html/ram.jar/de/dclj/ram/Function.html

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