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Difference between revisions of "FAQ How do I load and save plug-in preferences?"

m (Current Practice: Replaced deprecated constructor call to InstanceScope)
 
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==The Deprecated Way==
 
Each plug-in has a local workspace preference store for saving arbitrary primitive data types and strings. Preferences displayed in the Workbench Preferences dialog are typically stored in these local plug-in preference stores. The '''Import''' and '''Export''' buttons in the Workbench Preferences page also operate on these plug-in preference stores.
 
 
Retrieving values from plug-in preferences is fairly straightforward:
 
<pre>
 
  Plugin plugin = ExamplesPlugin.getDefault();
 
  Preferences prefs = plugin.getPluginPreferences();
 
  int value = prefs.getInt("some.key");
 
</pre>
 
When preferences are changed, the preference store must be explicitly saved to disk:
 
<pre>
 
  prefs.setValue("some.key", 5);
 
  plugin.savePluginPreferences();
 
</pre>
 
The plug-in preference store can also store default values for any preference in that plug-in. If a value has not been explicitly set for a given key, the default value is returned. If the key has no default value set, a default default value is used: zero for numeric preferences, <tt>false</tt> for Boolean preferences, and the empty string for string preferences. If the default default is not appropriate for your preference keys, you should establish a default value for each key by overriding the <tt>initializeDefaultPluginPreferences</tt> method in your <tt>Plugin</tt> subclass:
 
<pre>
 
  protected void initializeDefaultPluginPreferences() {
 
      prefs = plugin.<strike>getPluginPreferences</strike>();
 
      prefs.setDefault("some,key", 1);
 
  }
 
</pre>
 
Although you can change default values at any time, it is generally advised to keep them consistent so that users know what to expect when they revert preferences to their default values. Programmatically reverting a preference to its default value is accomplished with the <tt>setToDefault</tt> method.
 
 
 
 
 
== Current Practice ==
 
== Current Practice ==
The above technique has been deprecated since 3.1.
 
  
The current technique goes something like this:
+
As of 3.1 the technique to modify preference values goes something like this:
  
 
  private void savePluginSettings() {
 
  private void savePluginSettings() {
 
   // saves plugin preferences at the workspace level
 
   // saves plugin preferences at the workspace level
 
   Preferences prefs =
 
   Preferences prefs =
    //Platform.getPreferencesService().getRootNode().node(Plugin.PLUGIN_PREFEERENCES_SCOPE).node(MY_PLUGIN_ID);
 
 
     InstanceScope.INSTANCE.getNode(MY_PLUGIN_ID); // does all the above behind the scenes
 
     InstanceScope.INSTANCE.getNode(MY_PLUGIN_ID); // does all the above behind the scenes
 
   
 
   

Latest revision as of 05:53, 12 November 2014

Current Practice

As of 3.1 the technique to modify preference values goes something like this:

private void savePluginSettings() {
  // saves plugin preferences at the workspace level
  Preferences prefs =
    InstanceScope.INSTANCE.getNode(MY_PLUGIN_ID); // does all the above behind the scenes

  prefs.put(KEY1, this.someStr);
  prefs.put(KEY2, this.someBool);

  try {
    // prefs are automatically flushed during a plugin's "super.stop()".
    prefs.flush();
  } catch(BackingStoreException e) {
    //TODO write a real exception handler.
    e.printStackTrace();
  }
}

private void loadPluginSettings() {
  Preferences prefs = new InstanceScope().getNode(MY_PLUGIN_ID);
  // you might want to call prefs.sync() if you're worried about others changing your settings
  this.someStr = prefs.get(KEY1);
  this.someBool= prefs.getBoolean(KEY2);
}

See Also:


This FAQ was originally published in Official Eclipse 3.0 FAQs. Copyright 2004, Pearson Education, Inc. All rights reserved. This text is made available here under the terms of the Eclipse Public License v1.0.

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