Re: Binding to a POJO

From:
Tom Anderson <twic@urchin.earth.li>
Newsgroups:
comp.lang.java.programmer
Date:
Sat, 5 Mar 2011 19:02:37 +0000
Message-ID:
<alpine.DEB.1.10.1103051856160.15693@urchin.earth.li>
On Fri, 4 Mar 2011, Steve Sobol wrote:

The often-cited problem with either JGoodies or BeansBinding is this: it
introduces code bloat. Instead of

public void setFoo(Object newFoo) {
 this.foo=newFoo;
}

you have to do this:

public void setFoo(Object newFoo) {
 String oldFoo = this.foo;
 this.foo=newFoo;

 // support is a previously-initialized
 // instance of java.beans.PropertyChangeSupport

 support.firePropertyChange(propertyName, oldValue, newValue);
}

I came up with a solution that will allow you to do this instead:

public void setFoo(Object newFoo {
 changeProperty("foo",this.foo,newFoo);
}


Okay, how about:

public class PropertyChangeUtils {
  private static final PropertyChangeSupport support; // initialise this somehow
  public static <T> T change(String propertyName, T oldValue, T newValue) {
  support.firePropertyChange(propertyName, oldValue, newValue);
  return newValue;
  }
}

import static PropertyChangeUtils.change;

private String foo;
public void setFoo(Object foo) {
  this.foo = change("foo", this.foo, foo);
}

The code in the setter is fractionally (well, ~25%) more complicated than
with your version, but there's no reflection, and you have static type
safety.

It does fire the property change event before actually changing the
property, though; i don't know enough about Swing to know if that would be
a problem.

tom

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