My Own Java 7 Suggestion

I’d like to see an interface something like this:

public interface PropertyChangeSource {
  void addPropertyChangeListener(PropertyChangeListener l);
  void removePropertyChangeListener(PropertyChangeListener l);
}

I’m not sure if this would also have these additional methods, or if that requires another interface:

public interface NamedPropertyChangeSource extends PropertyChangeSource {
  void addPropertyChangeListener(String propertyName, PropertyChangeListener l);
  void removePropertyChangeListener(String propertyName, PropertyChangeListener l);
}

Of course PropertyChangeSupport would implement this interface, as would many other beans with these methods.

Why?

For example, here is some code from Glazed Lists‘ JavaBeanEventListConnector class:

public JavaBeanEventListConnector(Class<E> beanClass) {
  final Method[] methods = beanClass.getMethods();
  for (int m = 0; m < methods.length; m++) {
    if(methods[m].getParameterTypes().length != 1) continue;
    if(methods[m].getParameterTypes()[0] != PropertyChangeListener.class) continue;
    if(methods[m].getName().startsWith("add")) this.addListenerMethod = methods[m];
    if(methods[m].getName().startsWith("remove"))
        this.removeListenerMethod = methods[m];
  }
  if (this.addListenerMethod == null || this.removeListenerMethod == null)
    throw new IllegalArgumentException("Couldn't find listener methods for " +
        beanClass.getName());
  }

Admittedly, it would be difficult to change this particular class due to backwards compatibility concerns. But I know I’ve written very similar reflection code in some of my humble little projects where I work, and I’d rather just utilize an interface.

This is much like the Closeable interface added in Java 5.

This entry was posted on Monday, November 19th, 2007 at 10:01 am and is filed under Java. You can skip to the end and leave a response.