org.apache.tapestry5.dom

## Class Element

- java.lang.Object
- - org.apache.tapestry5.dom.Node
  - - org.apache.tapestry5.dom.Element

-     public final class Element
      extends Node

  An element that will render with a begin tag and attributes, a body, and an end tag. Also acts as a factory for enclosed Element, Text and Comment nodes.

  TODO: Support for CDATA nodes. Do we need Entity nodes?

- - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `Element` | `addClassName(String... classNames)` Deprecated. Deprecated in 5.4, as this is now special behavior for the "class" attribute.
    `Element` | `attribute(String name, String value)` Adds an attribute to the element, but only if the attribute name does not already exist.
    `Element` | `attribute(String namespace, String name, String value)` Adds a namespaced attribute to the element, but only if the attribute name does not already exist.
    `Element` | `attributes(String... namesAndValues)` Convenience for invoking `attribute(String, String)` multiple times.
    `CData` | `cdata(String content)` Adds and returns a new CDATA node.
    `Element` | `comment(String text)` Adds the comment and returns this element for further construction.
    `Element` | `defineNamespace(String namespace, String namespacePrefix)` Defines a namespace for this element, mapping a URI to a prefix.
    `Element` | `element(String name, String... namesAndValues)` Creates and returns a new Element node as a child of this node.
    `Element` | `elementAt(int index, String name, String... namesAndValues)` Creates a new element, as a child of the current index, at the indicated index.
    `Element` | `elementBefore(String name, String... namesAndValues)` Inserts a new element before this element.
    `Element` | `elementNS(String namespace, String name)` Creates and returns a new Element within a namespace as a child of this node.
    `Element` | `find(String path)` Searchs for a child element with a particular name below this element.
    `Element` | `forceAttributes(String... namesAndValues)` Forces changes to a number of attributes.
    `Element` | `forceAttributesNS(String namespace, String... namesAndValues)` Forces changes to a number of attributes in the global namespace.
    `String` | `getAttribute(String attributeName)`
    `Collection<Attribute>` | `getAttributes()` Returns the attributes for this Element as a (often empty) collection of `Attribute`s.
    `String` | `getChildMarkup()`
    `List<Node>` | `getChildren()` Returns an unmodifiable list of children for this element.
    `Document` | `getDocument()`
    `Element` | `getElement(Predicate<Element> predicate)` Tries to find an element under this element (including itself) accepted by the given predicate.
    `Element` | `getElementByAttributeValue(String attributeName, String attributeValue)` Tries to find an element under this element (including itself) whose given attribute has a given value.
    `Element` | `getElementById(String id)` Tries to find an element under this element (including itself) whose id is specified.
    `String` | `getName()`
    `String` | `getNamespace()` Returns the namespace for this element (which is typically a URL).
    `protected Map<String,String>` | `getNamespaceURIToPrefix()`
    `boolean` | `isEmpty()` Returns true if the element has no children, or has only text children that contain only whitespace.
    `void` | `pop()` Removes an element; the element's children take the place of the node within its container.
    `Element` | `raw(String text)` Adds the raw text and returns this element for further construction.
    `Element` | `removeChildren()` Removes all children from this element.
    `Text` | `text(String text)` Adds and returns a new text node (the text node is returned so that `Text.write(String)` or [@link `Text.writef(String, Object[])` may be invoked .
    `void` | `visit(Visitor visitor)` Depth-first visitor traversal of this Element and its Element children.

    - ### Methods inherited from class org.apache.tapestry5.dom.Node

      `getContainer, moveAfter, moveBefore, moveToBottom, moveToTop, remove, toMarkup, toString, wrap`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Method Detail

    - #### getDocument

          public Document getDocument()

      Overrides:
        `getDocument` in class `Node`

    - #### attribute

          public Element attribute(String name,
                          String value)

      Adds an attribute to the element, but only if the attribute name does not already exist. The "class" attribute is treated specially: the new value is appended, after a space, to the existing value.
      Parameters:
        `name` - the name of the attribute to add
        `value` - the value for the attribute. A value of null is allowed, and no attribute will be added to the element.

    - #### attribute

          public Element attribute(String namespace,
                          String name,
                          String value)

      Adds a namespaced attribute to the element, but only if the attribute name does not already exist. The "class" attribute of the default namespace is treated specially: the new value is appended, after a space, to the existing value.
      Parameters:
        `namespace` - the namespace to contain the attribute, or null for the default namespace
        `name` - the name of the attribute to add
        `value` - the value for the attribute. A value of null is allowed, and no attribute will be added to the element.

    - #### attributes

          public Element attributes(String... namesAndValues)

      Convenience for invoking `attribute(String, String)` multiple times.
      Parameters:
        `namesAndValues` - alternating attribute names and attribute values

    - #### forceAttributes

          public Element forceAttributes(String... namesAndValues)

      Forces changes to a number of attributes. The new attributes overwrite previous values. Overriding an attribute's value to null will remove the attribute entirely.
      Parameters:
        `namesAndValues` - alternating attribute names and attribute values
      Returns:
        this element

    - #### forceAttributesNS

          public Element forceAttributesNS(String namespace,
                                  String... namesAndValues)

      Forces changes to a number of attributes in the global namespace. The new attributes overwrite previous values (event for the "class" attribute). Overriding attribute's value to null will remove the attribute entirely. TAP5-708: don't use element namespace for attributes
      Parameters:
        `namespace` - the namespace or null
        `namesAndValues` - alternating attribute name and value
      Returns:
        this element

    - #### element

          public Element element(String name,
                        String... namesAndValues)

      Creates and returns a new Element node as a child of this node.
      Parameters:
        `name` - the name of the element to create
        `namesAndValues` - alternating attribute names and attribute values

    - #### elementBefore

          public Element elementBefore(String name,
                              String... namesAndValues)

      Inserts a new element before this element.
      Parameters:
        `name` - element name
        `namesAndValues` - attribute names and values
      Returns:
        the new element
      Since:
        5.3

    - #### elementNS

          public Element elementNS(String namespace,
                          String name)

      Creates and returns a new Element within a namespace as a child of this node.
      Parameters:
        `namespace` - namespace to contain the element, or null
        `name` - element name to create within the namespace
      Returns:
        the newly created element

    - #### elementAt

          public Element elementAt(int index,
                          String name,
                          String... namesAndValues)

      Creates a new element, as a child of the current index, at the indicated index.
      Parameters:
        `index` - to insert at
        `name` - element name
        `namesAndValues` - attribute name / attribute value pairs
      Returns:
        the new element

    - #### comment

          public Element comment(String text)

      Adds the comment and returns this element for further construction.

    - #### raw

          public Element raw(String text)

      Adds the raw text and returns this element for further construction.

    - #### text

          public Text text(String text)

      Adds and returns a new text node (the text node is returned so that `Text.write(String)` or [@link `Text.writef(String, Object[])` may be invoked .
      Parameters:
        `text` - initial text for the node
      Returns:
        the new Text node

    - #### cdata

          public CData cdata(String content)

      Adds and returns a new CDATA node.
      Parameters:
        `content` - the content to be rendered by the node
      Returns:
        the newly created node

    - #### getElementById

          public Element getElementById(String id)

      Tries to find an element under this element (including itself) whose id is specified. Performs a width-first search of the document tree.
      Parameters:
        `id` - the value of the id attribute of the element being looked for
      Returns:
        the element if found. null if not found.

    - #### getElementByAttributeValue

          public Element getElementByAttributeValue(String attributeName,
                                           String attributeValue)

      Tries to find an element under this element (including itself) whose given attribute has a given value.
      Parameters:
        `attributeName` - the name of the attribute of the element being looked for
        `attributeValue` - the value of the attribute of the element being looked for
      Returns:
        the element if found. null if not found.
      Since:
        5.2.3

    - #### getElement

          public Element getElement(Predicate<Element> predicate)

      Tries to find an element under this element (including itself) accepted by the given predicate.
      Parameters:
        `predicate` - Predicate to accept the element
      Returns:
        the element if found. null if not found.
      Since:
        5.2.3

    - #### find

          public Element find(String path)

      Searchs for a child element with a particular name below this element. The path parameter is a slash separated series of element names.

    - #### getAttribute

          public String getAttribute(String attributeName)

    - #### getName

          public String getName()

    - #### addClassName

          public Element addClassName(String... classNames)

      Deprecated. Deprecated in 5.4, as this is now special behavior for the "class" attribute.
      Adds one or more CSS class names to the "class" attribute.
      Parameters:
        `classNames` - one or more CSS class names
      Returns:
        the element for further configuration

    - #### defineNamespace

          public Element defineNamespace(String namespace,
                                String namespacePrefix)

      Defines a namespace for this element, mapping a URI to a prefix. This will affect how namespaced elements and attributes nested within the element are rendered, and will also cause `xmlns:` attributes (to define the namespace and prefix) to be rendered.
      Parameters:
        `namespace` - URI of the namespace
        `namespacePrefix` - prefix
      Returns:
        this element

    - #### getNamespace

          public String getNamespace()

      Returns the namespace for this element (which is typically a URL). The namespace may be null.

    - #### pop

          public void pop()

      Removes an element; the element's children take the place of the node within its container.

    - #### removeChildren

          public Element removeChildren()

      Removes all children from this element.
      Returns:
        the element, for method chaining

    - #### getNamespaceURIToPrefix

          protected Map<String,String> getNamespaceURIToPrefix()

      Overrides:
        `getNamespaceURIToPrefix` in class `Node`

    - #### isEmpty

          public boolean isEmpty()

      Returns true if the element has no children, or has only text children that contain only whitespace.
      Since:
        5.1.0.0

    - #### visit

          public void visit(Visitor visitor)

      Depth-first visitor traversal of this Element and its Element children. The traversal order is the same as render order.
      Parameters:
        `visitor` - callback
      Since:
        5.1.0.0

    - #### getChildMarkup

          public final String getChildMarkup()

      Returns:
        the concatenation of the String representations `Node.toString()` of its children.

    - #### getChildren

          public List<Node> getChildren()

      Returns an unmodifiable list of children for this element. Only `Element`s will have children. Also, note that unlike W3C DOM, attributes are not represented as `Node`s.
      Returns:
        unmodifiable list of children nodes

    - #### getAttributes

          public Collection<Attribute> getAttributes()

      Returns the attributes for this Element as a (often empty) collection of `Attribute`s. The order of the attributes within the collection is not specified. Modifying the collection will not affect the attributes (use `forceAttributes(String[])` to change existing attribute values, and `attribute(String, String, String)` to add new attribute values.
      Returns:
        attribute collection

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