Java XML Element Children getSubelementDouble(final Element element, final String name, final double default_value)

Description

Locate a sub-element tagged 'name', return its value.

License

Open Source License

Parameter

Parameter	Description
element	Element where to start looking. May be null.
name	Name of sub-element to locate.
default_value	Default value if not found

Exception

Parameter	Description
Exception	on error in number format

Return

Returns double string that was found

Declaration

final public static double getSubelementDouble(final Element element, final String name,
        final double default_value) throws Exception 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright (c) 2012 Oak Ridge National Laboratory.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 ******************************************************************************/

import org.w3c.dom.Element;
import org.w3c.dom.Node;

public class Main {
    /** Locate a sub-element tagged 'name', return its value.
     *//from  ww  w .  j  a va  2  s  . c  o  m
     *  @param element Element where to start looking. May be null.
     *  @param name Name of sub-element to locate.
     *
     *  @return Returns string that was found or NaN
     *  @throws Exception on error in number format
     */
    final public static double getSubelementDouble(final Element element, final String name) throws Exception {
        return getSubelementDouble(element, name, Double.NaN);
    }

    /** Locate a sub-element tagged 'name', return its value.
    *
    *  @param element Element where to start looking. May be null.
    *  @param name Name of sub-element to locate.
    *  @param default_value Default value if not found
    *
    *  @return Returns double string that was found
    *  @throws Exception on error in number format
    */
    final public static double getSubelementDouble(final Element element, final String name,
            final double default_value) throws Exception {
        final String text = getSubelementString(element, name, "").trim();
        if (text.isEmpty())
            return default_value;
        try {
            return Double.parseDouble(text);
        } catch (NumberFormatException ex) {
            throw new Exception("Invalid number for <" + name + ">", ex);
        }
    }

    /** Locate a sub-element tagged 'name', return its value.
     *
     *  Will only go one level down, not search the whole tree.
     *
     *  @param element Element where to start looking. May be null.
     *  @param name Name of sub-element to locate.
     *  @param default_value Default value if not found
     *
     *  @return Returns string that was found or default_value.
     */
    final public static String getSubelementString(final Element element, final String name,
            final String default_value) {
        if (element == null)
            return default_value;
        Node n = element.getFirstChild();
        n = findFirstElementNode(n, name);
        return getString(n, default_value);
    }

    /** Look for Element node if given name.
     *  <p>
     *  Checks the node and its siblings.
     *  Does not descent down the 'child' links.
     *  @param node Node where to start.
     *  @param name Name of the nodes to look for.
     *  @return Returns node or the next matching sibling or null.
     */
    final public static Element findFirstElementNode(Node node, final String name) {
        while (node != null) {
            if (node.getNodeType() == Node.ELEMENT_NODE && node.getNodeName().equals(name))
                return (Element) node;
            node = node.getNextSibling();
        }
        return null;
    }

    final public static String getString(final Node node, final String default_value) {
        if (node != null) {
            Node text_node = node.getFirstChild();
            if (text_node == null)
                return default_value;
            return text_node.getNodeValue();
        }
        return default_value;
    }
}

Related

1. getRelationUri(Element subject, Element object, String defaultBaseUri)
2. getSubElement(Element ele, String tagName)
3. getSubElement(Element element, String subTagName)
4. getSubelementBoolean(final Element element, final String element_name, final boolean default_value)
5. getSubelementDouble(final Element element, final String element_name)
6. getSubelementString(final Element element, final String name)
7. getSubelementString(final Element element, final String name)
8. getSubelementString(final Element element, final String name, final String default_value)
9. getSubelementStrings(final Element element, final String name)