Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.configuration.tree; import java.util.List; /** * <p> * Definition of an interface for the nodes of a hierarchical configuration. * </p> * <p> * This interface defines a tree like structure for configuration data. A node * has a value and can have an arbitrary number of children and attribures. * </p> * * @since 1.3 * @author Oliver Heger * @version $Id: ConfigurationNode.java 439648 2006-09-02 20:42:10Z oheger $ */ public interface ConfigurationNode { /** * Returns the name of this node. * * @return the node name */ String getName(); /** * Sets the name of this node. * * @param name the node name */ void setName(String name); /** * Returns the value of this node. * * @return the node's value */ Object getValue(); /** * Sets the value of this node. * * @param val the node's value */ void setValue(Object val); /** * Returns this node's reference. * * @return the reference */ Object getReference(); /** * Sets this node's reference. This reference can be used by concrete * Configuration implementations to store data associated with each node. A * XML based configuration for instance could here store a reference to the * corresponding DOM element. * * @param ref the reference */ void setReference(Object ref); /** * Returns this node's parent. Can be <b>null</b>, then this node is the * top level node. * * @return the parent of this node */ ConfigurationNode getParentNode(); /** * Sets the parent of this node. * * @param parent the parent of this node */ void setParentNode(ConfigurationNode parent); /** * Adds a child to this node. * * @param node the new child */ void addChild(ConfigurationNode node); /** * Returns a list with the child nodes of this node. The nodes in this list * should be in the order they were inserted into this node. * * @return a list with the children of this node (never <b>null</b>) */ List getChildren(); /** * Returns the number of this node's children. * * @return the number of the children of this node */ int getChildrenCount(); /** * Returns a list with all children of this node with the given name. * * @param name the name of the searched children * @return a list with all child nodes with this name (never <b>null</b>) */ List getChildren(String name); /** * Returns the number of children with the given name. * * @param name the name * @return the number of children with this name */ int getChildrenCount(String name); /** * Returns the child node with the given index. If the index does not * exist, an exception will be thrown. * @param index the index of the child node (0-based) * @return the child node with this index */ ConfigurationNode getChild(int index); /** * Removes the given node from this node's children. * * @param child the child node to be removed * @return a flag if the node could be removed */ boolean removeChild(ConfigurationNode child); /** * Removes all child nodes of this node with the given name. * * @param childName the name of the children to be removed * @return a flag if at least one child was removed */ boolean removeChild(String childName); /** * Removes all children from this node. */ void removeChildren(); /** * Returns a flag whether this node is an attribute. * * @return a flag whether this node is an attribute */ boolean isAttribute(); /** * Sets a flag whether this node is an attribute. * * @param f the attribute flag */ void setAttribute(boolean f); /** * Returns a list with this node's attributes. Attributes are also modeled * as <code>ConfigurationNode</code> objects. * * @return a list with the attributes */ List getAttributes(); /** * Returns the number of attributes of this node. * @return the number of attributes */ int getAttributeCount(); /** * Returns a list with the attribute nodes with the given name. Attributes * with same names can be added multiple times, so the return value of this * method is a list. * * @param name the name of the attribute * @return the attribute nodes with this name (never <b>null</b>) */ List getAttributes(String name); /** * Returns the number of attributes with the given name. * * @param name the name of the attribute * @return the number of attributes with this name */ int getAttributeCount(String name); /** * Returns the attribute node with the given index. If no such index exists, * an exception will be thrown. * @param index the index * @return the attribute node with this index */ ConfigurationNode getAttribute(int index); /** * Removes the specified attribute from this node. * * @param node the attribute to remove * @return a flag if the node could be removed */ boolean removeAttribute(ConfigurationNode node); /** * Removes all attributes with the given name. * * @param name the name of the attributes to be removed * @return a flag if at least one attribute was removed */ boolean removeAttribute(String name); /** * Removes all attributes of this node. */ void removeAttributes(); /** * Adds the specified attribute to this node * * @param attr the attribute node */ void addAttribute(ConfigurationNode attr); /** * Returns a flag if this node is defined. This means that the node contains * some data. * * @return a flag whether this node is defined */ boolean isDefined(); /** * Visits this node and all its sub nodes. This method provides a simple * means for going through a hierarchical structure of configuration nodes. * * @see ConfigurationNodeVisitor * @param visitor the visitor */ void visit(ConfigurationNodeVisitor visitor); /** * Returns a copy of this node. * @return the copy */ Object clone(); }