Package java.util.prefs

Package java.util.prefs

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Java 1.4

The java.util.prefs package contains classes and interfaces for managing persistant user and system-wide preferences for Java applications and classes. Most applications will use only the Preferences class itself. Some will also use the event objects and listener interfaces defined by this package, and some may need to explicitly catch the types of exceptions defined by this package. Application programmers never need to use the PreferencesFactory interface or the AbstractPreferences class, which are intended for Preferences implementors only.

To use the Preferences class, first use a static method to obtain an appropriate Preferences object or objects, and then use a get( ) method to query a preference value or a put( ) method to set a preference value. The code below shows a typical usage. See the Preferences class for details.

 import java.util.prefs.Preferences; public class TextEditor {   // some constants that define default values for preferences   public static final int WIDTH_DEFAULT = 80;   public static final String DICTIONARY_DEFAULT = "";   // Fields to be initialized from preference values   public int width;             // Screen width in columns   public String dictionary;     // Dictionary name for spell-checking   public void initPrefs( ) {     // Get Preferences objects for user and system preferences for this package     Preferences userprefs = Preferences.userNodeForPackage(TextEditor.class);     Preferences sysprefs = Preferences.systemNodeForPackage(TextEditor.class);     // Look up preference values.  Note that we always pass a default value     width = userprefs.getInt("width", WIDTH_DEFAULT);     // Look up a user preference using a system preference as the default     dictionary = userprefs.get("dictionary",                                sysprefs.get("dictionary",                                             DICTIONARY_DEFAULT));   } } 

Interfaces

 public interface  NodeChangeListener  extends java.util.EventListener; public interface  PreferenceChangeListener  extends java.util.EventListener; public interface  PreferencesFactory  ; 

Events

 public class  NodeChangeEvent  extends java.util.EventObject; public class  PreferenceChangeEvent  extends java.util.EventObject; 

Other Classes

 public abstract class  Preferences  ;    public abstract class  AbstractPreferences  extends Preferences; 

Exceptions

 public class  BackingStoreException  extends Exception; public class  InvalidPreferencesFormatException  extends Exception;