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@Preferences get injected even they don't change [message #1097168]

Thu, 29 August 2013 10:18

Nepomuk Seiler

Messages: 88
Registered: December 2010

Member

Hi,

I have a problem with the injection-based listener approach. Values get injected, even if they haven't changed.

I have a handler class which contains these values these methods

@Inject
public void trackDatabaseDriver(@Preference("jdbc_driver") String driver) {
	System.out.println("\tDriver   :\t" + driver);
}

@Inject
public void trackDatabaseURL(@Preference("jdbc_url") String url) {
	System.out.println("\tURL   :\t" + url);
}

And another handler which does this


@Inject
@Preference
IEclipsePreferences preferences;

@Execute
public void execute() throws Exception {
    // doesn't matter where/if I put preferences.flush()
    preferences.put("jdbc_driver", "org.apache.derby.jdbc.EmbeddedDriver");
    preferences.put("jdbc_url", "jdbc:derby:memory:test2;create=true");
}

The flow is as follows.

Application start

Quote:

URL : null
Driver : null

I'm not completely sure why the values get injected, even they didn't changed.

[b]Click SavenPreferencesHandler[b]

Quote:

URL : null
Driver : org.apache.derby.jdbc.EmbeddedDriver
URL : jdbc:derby:memory:test2;create=true
Driver : org.apache.derby.jdbc.EmbeddedDriver

The methods are called twice. Both. Even though I only changed each preference once.

If I use the PreferenceChangeListener it works smooth.

preferences.addPreferenceChangeListener(new IPreferenceChangeListener() {

    @Override
    public void preferenceChange(PreferenceChangeEvent event) {
            System.err.println("KEY " + event.getKey());
            System.err.println("NEW " + event.getNewValue());
            System.err.println("OLD " + event.getOldValue());
        }
    });

Do I have to put the preferences all in different nodes?

thanks,
Muki

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