HTMLDocument.HTMLReader (Java Platform SE 8 )
Keywords: javax.swing.text.html.HTMLDocument.HTMLReader class
Date: 2026-06-25

javax.swing.text.html

## Class HTMLDocument.HTMLReader

- java.lang.Object
- - javax.swing.text.html.HTMLEditorKit.ParserCallback
  - - javax.swing.text.html.HTMLDocument.HTMLReader

- Enclosing class:
    HTMLDocument

      public class HTMLDocument.HTMLReader
      extends HTMLEditorKit.ParserCallback

  An HTML reader to load an HTML document with an HTML element structure. This is a set of callbacks from the parser, implemented to create a set of elements tagged with attributes. The parse builds up tokens (ElementSpec) that describe the element subtree desired, and burst it into the document under the protection of a write lock using the insert method on the document outer class.

  The reader can be configured by registering actions (of type `HTMLDocument.HTMLReader.TagAction`) that describe how to handle the action. The idea behind the actions provided is that the most natural text editing operations can be provided if the element structure boils down to paragraphs with runs of some kind of style in them. Some things are more naturally specified structurally, so arbitrary structure should be allowed above the paragraphs, but will need to be edited with structural actions. The implication of this is that some of the HTML elements specified in the stream being parsed will be collapsed into attributes, and in some cases paragraphs will be synthesized. When HTML elements have been converted to attributes, the attribute key will be of type HTML.Tag, and the value will be of type AttributeSet so that no information is lost. This enables many of the existing actions to work so that the user can type input, hit the return key, backspace, delete, etc and have a reasonable result. Selections can be created, and attributes applied or removed, etc. With this in mind, the work done by the reader can be categorized into the following kinds of tasks:

  Block
    Build the structure like it's specified in the stream. This produces elements that contain other elements.
  Paragraph
    Like block except that it's expected that the element will be used with a paragraph view so a paragraph element won't need to be synthesized.
  Character
    Contribute the element as an attribute that will start and stop at arbitrary text locations. This will ultimately be mixed into a run of text, with all of the currently flattened HTML character elements.
  Special
    Produce an embedded graphical element.
  Form
    Produce an element that is like the embedded graphical element, except that it also has a component model associated with it.
  Hidden
    Create an element that is hidden from view when the document is being viewed read-only, and visible when the document is being edited. This is useful to keep the model from losing information, and used to store things like comments and unrecognized tags.

  Currently, <APPLET>, <PARAM>, <MAP>, <AREA>, <LINK>, <SCRIPT> and <STYLE> are unsupported.

  The assignment of the actions described is shown in the following table for the tags defined in `HTML.Tag`.

  Tag | Action
  --- | ---
  `HTML.Tag.A` | CharacterAction
  `HTML.Tag.ADDRESS` | CharacterAction
  `HTML.Tag.APPLET` | HiddenAction
  `HTML.Tag.AREA` | AreaAction
  `HTML.Tag.B` | CharacterAction
  `HTML.Tag.BASE` | BaseAction
  `HTML.Tag.BASEFONT` | CharacterAction
  `HTML.Tag.BIG` | CharacterAction
  `HTML.Tag.BLOCKQUOTE` | BlockAction
  `HTML.Tag.BODY` | BlockAction
  `HTML.Tag.BR` | SpecialAction
  `HTML.Tag.CAPTION` | BlockAction
  `HTML.Tag.CENTER` | BlockAction
  `HTML.Tag.CITE` | CharacterAction
  `HTML.Tag.CODE` | CharacterAction
  `HTML.Tag.DD` | BlockAction
  `HTML.Tag.DFN` | CharacterAction
  `HTML.Tag.DIR` | BlockAction
  `HTML.Tag.DIV` | BlockAction
  `HTML.Tag.DL` | BlockAction
  `HTML.Tag.DT` | ParagraphAction
  `HTML.Tag.EM` | CharacterAction
  `HTML.Tag.FONT` | CharacterAction
  `HTML.Tag.FORM` | As of 1.4 a BlockAction
  `HTML.Tag.FRAME` | SpecialAction
  `HTML.Tag.FRAMESET` | BlockAction
  `HTML.Tag.H1` | ParagraphAction
  `HTML.Tag.H2` | ParagraphAction
  `HTML.Tag.H3` | ParagraphAction
  `HTML.Tag.H4` | ParagraphAction
  `HTML.Tag.H5` | ParagraphAction
  `HTML.Tag.H6` | ParagraphAction
  `HTML.Tag.HEAD` | HeadAction
  `HTML.Tag.HR` | SpecialAction
  `HTML.Tag.HTML` | BlockAction
  `HTML.Tag.I` | CharacterAction
  `HTML.Tag.IMG` | SpecialAction
  `HTML.Tag.INPUT` | FormAction
  `HTML.Tag.ISINDEX` | IsndexAction
  `HTML.Tag.KBD` | CharacterAction
  `HTML.Tag.LI` | BlockAction
  `HTML.Tag.LINK` | LinkAction
  `HTML.Tag.MAP` | MapAction
  `HTML.Tag.MENU` | BlockAction
  `HTML.Tag.META` | MetaAction
  `HTML.Tag.NOFRAMES` | BlockAction
  `HTML.Tag.OBJECT` | SpecialAction
  `HTML.Tag.OL` | BlockAction
  `HTML.Tag.OPTION` | FormAction
  `HTML.Tag.P` | ParagraphAction
  `HTML.Tag.PARAM` | HiddenAction
  `HTML.Tag.PRE` | PreAction
  `HTML.Tag.SAMP` | CharacterAction
  `HTML.Tag.SCRIPT` | HiddenAction
  `HTML.Tag.SELECT` | FormAction
  `HTML.Tag.SMALL` | CharacterAction
  `HTML.Tag.STRIKE` | CharacterAction
  `HTML.Tag.S` | CharacterAction
  `HTML.Tag.STRONG` | CharacterAction
  `HTML.Tag.STYLE` | StyleAction
  `HTML.Tag.SUB` | CharacterAction
  `HTML.Tag.SUP` | CharacterAction
  `HTML.Tag.TABLE` | BlockAction
  `HTML.Tag.TD` | BlockAction
  `HTML.Tag.TEXTAREA` | FormAction
  `HTML.Tag.TH` | BlockAction
  `HTML.Tag.TITLE` | TitleAction
  `HTML.Tag.TR` | BlockAction
  `HTML.Tag.TT` | CharacterAction
  `HTML.Tag.U` | CharacterAction
  `HTML.Tag.UL` | BlockAction
  `HTML.Tag.VAR` | CharacterAction

  Once </html> is encountered, the Actions are no longer notified.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `class` | `HTMLDocument.HTMLReader.BlockAction`
    `class` | `HTMLDocument.HTMLReader.CharacterAction`
    `class` | `HTMLDocument.HTMLReader.FormAction` Action to support forms by building all of the elements used to represent form controls.
    `class` | `HTMLDocument.HTMLReader.HiddenAction`
    `class` | `HTMLDocument.HTMLReader.IsindexAction`
    `class` | `HTMLDocument.HTMLReader.ParagraphAction`
    `class` | `HTMLDocument.HTMLReader.PreAction`
    `class` | `HTMLDocument.HTMLReader.SpecialAction`
    `class` | `HTMLDocument.HTMLReader.TagAction` An action to be performed in response to parsing a tag.

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected MutableAttributeSet` | `charAttr`
    `protected Vector<DefaultStyledDocument.ElementSpec>` | `parseBuffer`

    - ### Fields inherited from class javax.swing.text.html.HTMLEditorKit.ParserCallback

      `IMPLIED`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `HTMLReader(int offset)`
    `HTMLReader(int offset, int popDepth, int pushDepth, HTML.Tag insertTag)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected void` | `addContent(char[] data, int offs, int length)` Adds some text with the current character attributes.
    `protected void` | `addContent(char[] data, int offs, int length, boolean generateImpliedPIfNecessary)` Adds some text with the current character attributes.
    `protected void` | `addSpecialElement(HTML.Tag t, MutableAttributeSet a)` Adds content that is basically specified entirely in the attribute set.
    `protected void` | `blockClose(HTML.Tag t)` Adds an instruction to the parse buffer to close out a block element of the given type.
    `protected void` | `blockOpen(HTML.Tag t, MutableAttributeSet attr)` Adds an instruction to the parse buffer to create a block element with the given attributes.
    `void` | `flush()` The last method called on the reader.
    `void` | `handleComment(char[] data, int pos)`
    `void` | `handleEndOfLineString(String eol)` This is invoked after the stream has been parsed, but before `flush`.
    `void` | `handleEndTag(HTML.Tag t, int pos)` Callback from the parser.
    `void` | `handleSimpleTag(HTML.Tag t, MutableAttributeSet a, int pos)` Callback from the parser.
    `void` | `handleStartTag(HTML.Tag t, MutableAttributeSet a, int pos)` Callback from the parser.
    `void` | `handleText(char[] data, int pos)` Called by the parser to indicate a block of text was encountered.
    `protected void` | `popCharacterStyle()` Pops a previously pushed character style off the stack to return to a previous style.
    `protected void` | `preContent(char[] data)` Adds the given content that was encountered in a PRE element.
    `protected void` | `pushCharacterStyle()` Pushes the current character style on a stack in preparation for forming a new nested character style.
    `protected void` | `registerTag(HTML.Tag t, HTMLDocument.HTMLReader.TagAction a)` Registers a handler for the given tag.
    `protected void` | `textAreaContent(char[] data)` Adds the given content to the textarea document.

    - ### Methods inherited from class javax.swing.text.html.HTMLEditorKit.ParserCallback

      `handleError`

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

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

- - ### Field Detail

    - #### parseBuffer

          protected Vector<DefaultStyledDocument.ElementSpec> parseBuffer

    - #### charAttr

          protected MutableAttributeSet charAttr

  - ### Constructor Detail

    - #### HTMLReader

          public HTMLReader(int offset)

    - #### HTMLReader

          public HTMLReader(int offset,
                            int popDepth,
                            int pushDepth,
                            HTML.Tag insertTag)

  - ### Method Detail

    - #### flush

          public void flush()
                     throws BadLocationException

      The last method called on the reader. It allows any pending changes to be flushed into the document. Since this is currently loading synchronously, the entire set of changes are pushed in at this point.
      Overrides:
        `flush` in class `HTMLEditorKit.ParserCallback`
      Throws:
        `BadLocationException`

    - #### handleText

          public void handleText(char[] data,
                                 int pos)

      Called by the parser to indicate a block of text was encountered.
      Overrides:
        `handleText` in class `HTMLEditorKit.ParserCallback`

    - #### handleStartTag

          public void handleStartTag(HTML.Tag t,
                                     MutableAttributeSet a,
                                     int pos)

      Callback from the parser. Route to the appropriate handler for the tag.
      Overrides:
        `handleStartTag` in class `HTMLEditorKit.ParserCallback`

    - #### handleComment

          public void handleComment(char[] data,
                                    int pos)

      Overrides:
        `handleComment` in class `HTMLEditorKit.ParserCallback`

    - #### handleEndTag

          public void handleEndTag(HTML.Tag t,
                                   int pos)

      Callback from the parser. Route to the appropriate handler for the tag.
      Overrides:
        `handleEndTag` in class `HTMLEditorKit.ParserCallback`

    - #### handleSimpleTag

          public void handleSimpleTag(HTML.Tag t,
                                      MutableAttributeSet a,
                                      int pos)

      Callback from the parser. Route to the appropriate handler for the tag.
      Overrides:
        `handleSimpleTag` in class `HTMLEditorKit.ParserCallback`

    - #### handleEndOfLineString

          public void handleEndOfLineString(String eol)

      This is invoked after the stream has been parsed, but before `flush`. `eol` will be one of \n, \r or \r\n, which ever is encountered the most in parsing the stream.
      Overrides:
        `handleEndOfLineString` in class `HTMLEditorKit.ParserCallback`
      Since:
        1.3

    - #### registerTag

          protected void registerTag(HTML.Tag t,
                                     HTMLDocument.HTMLReader.TagAction a)

      Registers a handler for the given tag. By default all of the well-known tags will have been registered. This can be used to change the handling of a particular tag or to add support for custom tags.

    - #### pushCharacterStyle

          protected void pushCharacterStyle()

      Pushes the current character style on a stack in preparation for forming a new nested character style.

    - #### popCharacterStyle

          protected void popCharacterStyle()

      Pops a previously pushed character style off the stack to return to a previous style.

    - #### textAreaContent

          protected void textAreaContent(char[] data)

      Adds the given content to the textarea document. This method gets called when we are in a textarea context. Therefore all text that is seen belongs to the text area and is hence added to the TextAreaDocument associated with the text area.

    - #### preContent

          protected void preContent(char[] data)

      Adds the given content that was encountered in a PRE element. This synthesizes lines to hold the runs of text, and makes calls to addContent to actually add the text.

    - #### blockOpen

          protected void blockOpen(HTML.Tag t,
                                   MutableAttributeSet attr)

      Adds an instruction to the parse buffer to create a block element with the given attributes.

    - #### blockClose

          protected void blockClose(HTML.Tag t)

      Adds an instruction to the parse buffer to close out a block element of the given type.

    - #### addContent

          protected void addContent(char[] data,
                                    int offs,
                                    int length)

      Adds some text with the current character attributes.
      Parameters:
        `data` - the content to add
        `offs` - the initial offset
        `length` - the length

    - #### addContent

          protected void addContent(char[] data,
                                    int offs,
                                    int length,
                                    boolean generateImpliedPIfNecessary)

      Adds some text with the current character attributes.
      Parameters:
        `data` - the content to add
        `offs` - the initial offset
        `length` - the length
        `generateImpliedPIfNecessary` - whether to generate implied paragraphs

    - #### addSpecialElement

          protected void addSpecialElement(HTML.Tag t,
                                           MutableAttributeSet a)

      Adds content that is basically specified entirely in the attribute set.

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