Java : Comment (XML) with Examples

Comment (Java SE 22 & JDK 22) with Examples.
You will find code examples on most Comment methods.


Summary

This interface inherits from CharacterData and represents the content of a comment, i.e., all the characters between the starting '<!--' and ending '-->'. Note that this is the definition of a comment in XML, and, in practice, HTML, although some HTML tools may implement the full SGML comment structure.

Class diagram

final var xml = """
        <root>aaa<!--XYZ-->bbb</root>
        """;

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var root = document.getDocumentElement();
System.out.println(root); // [root: null]

final var nodes = root.getChildNodes();
System.out.println("-- nodes --");
for (int i = 0; i < nodes.getLength(); i++) {
    System.out.println(nodes.item(i));
}

// Result
// ↓
//-- nodes --
//[#text: aaa]
//[#comment: XYZ]
//[#text: bbb]
final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
final var document = builder.newDocument();

final var root = document.createElement("root");
System.out.println(root); // [root: null]

document.appendChild(root);

final var comment = document.createComment("abcd");
System.out.println(comment); // [#comment: abcd]
System.out.println(comment.getData()); // abcd

root.appendChild(comment);

final var transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

final var result = new StreamResult(new StringWriter());
transformer.transform(new DOMSource(document), result);

//<root><!--abcd--></root>
System.out.println(result.getWriter());

Fields declared in Node

ATTRIBUTE_NODE, CDATA_SECTION_NODE, COMMENT_NODE, DOCUMENT_FRAGMENT_NODE, DOCUMENT_NODE, DOCUMENT_POSITION_CONTAINED_BY, DOCUMENT_POSITION_CONTAINS, DOCUMENT_POSITION_DISCONNECTED, DOCUMENT_POSITION_FOLLOWING, DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC, DOCUMENT_POSITION_PRECEDING, DOCUMENT_TYPE_NODE, ELEMENT_NODE, ENTITY_NODE, ENTITY_REFERENCE_NODE, NOTATION_NODE, PROCESSING_INSTRUCTION_NODE, TEXT_NODE

Please see the link below.

Methods declared in CharacterData

appendData, deleteData, getData, getLength, insertData, replaceData, setData, substringData

Please see the link below.

Methods declared in Node

appendChild, cloneNode, compareDocumentPosition, getAttributes, getBaseURI, getChildNodes, getFeature, getFirstChild, getLastChild, getLocalName, getNamespaceURI, getNextSibling, getNodeName, getNodeType, getNodeValue, getOwnerDocument, getParentNode, getPrefix, getPreviousSibling, getTextContent, getUserData, hasAttributes, hasChildNodes, insertBefore, isDefaultNamespace, isEqualNode, isSameNode, isSupported, lookupNamespaceURI, lookupPrefix, normalize, removeChild, replaceChild, setNodeValue, setPrefix, setTextContent, setUserData

Please see the link below.


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