e408. removing a preference from a preference node.txt

这里面包含了一百多个JAVA源文件

// Get the user preference node for java.lang
    Preferences prefs = Preferences.userNodeForPackage(String.class);
    
    // Remove a preference in the node
    final String PREF_NAME = "name_of_preference";
    prefs.remove(PREF_NAME);
    
    // Remove all preferences in the node
    try {
        prefs.clear();
    } catch (BackingStoreException e) {
    }