src/plugins/emulator/src/com/motorola/studio/android/emulator/core/emulationui/EmuViewerNode.java

/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed 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 com.motorola.studio.android.emulator.core.emulationui;

import java.util.HashSet;
import java.util.Set;

/**
 * DESCRIPTION:
 * This class represents a node in the tree presented in a emulation view
 *
 * RESPONSIBILITY:
 * Guarantee the tree structure by maintaining the parent/child relationship
 *
 * COLABORATORS:
 * None.
 *
 * USAGE:
 * A class should construct an instance of this class whenever it wishes
 * to add a node to an emulation view tree 
 */
public class EmuViewerNode
{
    /**
     * The parent node of this node
     */
    private final EmuViewerNode parent;

    /**
     * An id that identifies the node type.
     * The id meaning is defined by the user
     */
    private final String nodeId;

    /**
     * The error message to use as the node label
     * If <code>null</code>, use regular label resolution
     */
    private String errorMessage = null;

    /**
     * A set containing all children of this node
     */
    private final Set<EmuViewerNode> children = new HashSet<EmuViewerNode>();

    /**
     * Constructor. 
     * 
     * @param parent The parent node of this node
     * @param nodeId An id that identifies the node type
     */
    public EmuViewerNode(EmuViewerNode parent, String nodeId)
    {
        this.parent = parent;
        this.nodeId = nodeId;
    }

    /**
     * Retrieves the node's parent
     * 
     * @return The parent node
     */
    public EmuViewerNode getParent()
    {
        return parent;
    }

    /**
     * Retrieves the id of this node. The id meaning is defined by the class user
     * 
     * @return The id of this node
     */
    public String getNodeId()
    {
        return nodeId;
    }

    /**
     * Adds a new child to this node
     * 
     * @param child The child to be added to the node
     */
    public void addChild(EmuViewerNode child)
    {
        children.add(child);
    }

    /**
     * Retrieves all this node's children 
     * 
     * @return A set containing all children of this node
     */
    public Set<EmuViewerNode> getChildren()
    {
        return children;
    }

    /**
     * Sets an error message to display as the node label.
     * If <code>null</code>, the regular label resolution is used
     * 
     * @param errorMessage An error message to display or <code>null</code> if it is 
     *                     desired to have regular label resolution for this node
     */
    public void setErrorMessage(String errorMessage)
    {
        this.errorMessage = errorMessage;
    }

    /**
     * Tests if this node has an error message assigned
     * 
     * @return True if an error message was assigned; false otherwise
     */
    public boolean hasErrorMessage()
    {
        return errorMessage != null;
    }

    /**
     * Retrieves the error message assigned to this node
     * 
     * @return The error message, or <code>null</code> if no error message was assigned
     */
    public String getErrorMessage()
    {
        return errorMessage;
    }

    /**
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString()
    {
        // For generic/intermediate nodes use the node id itself
        return getNodeId();
    }
}