e414. removing a preference node.txt

来自「这里面包含了一百多个JAVA源文件」· 文本 代码 · 共 34 行

Removing a preference node will remove all of the node's descendants. 
See also e415 Determining If a Preference Node Exists. 

    try {
        // First check to see if the node is already removed;
        // otherwise, getting the node will automatically create it
        boolean exists = Preferences.userRoot().nodeExists("/foo"); // false
    
        if (!exists) {
            // Get the node
            Preferences prefs = Preferences.userRoot().node("/foo");
    
            // Remove the node
            prefs.removeNode();
    
            // Trying to remove it again would cause an IllegalStateException
            //prefs.removeNode();
        }
    
        // Create a node with a child
        Preferences prefs = Preferences.userRoot().node("/foo/child");
        exists = Preferences.userRoot().nodeExists("/foo");       // true
        exists = Preferences.userRoot().nodeExists("/foo/child"); // true
    
        // Remove the parent node
        Preferences.userRoot().node("/foo").removeNode();
    
        // Both parent and child are removed
        exists = Preferences.userRoot().nodeExists("/foo");       // false
        exists = Preferences.userRoot().nodeExists("/foo/child"); // false
    } catch (BackingStoreException e) {
    }