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Java : Element (XML) with Examples

September 11, 2024 May 9, 2022

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


Summary

The Element interface represents an element in an HTML or XML document. Elements may have attributes associated with them; since the Element interface inherits from Node, the generic Node interface attribute attributes may be used to retrieve the set of all attributes for an element.

Element (Java SE 22 & JDK 22)

Class diagram

Code examples on this page use the printDocument method below.

public void printDocument(Document document) throws TransformerException {
    final var transformer = TransformerFactory.newInstance().newTransformer();
    transformer.setOutputProperty(OutputKeys.INDENT, "yes");
    transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

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

    System.out.print(result.getWriter());
}

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

root.appendChild(child);

final var text = document.createTextNode("abcd");
System.out.println(text); // [#text: abcd]

child.appendChild(text);

//<root>
//    <child>abcd</child>
//</root>
printDocument(document);

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

String getAttribute (String name)

Retrieves an attribute value by name.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root>
            <child aa="AA" bb="BB" />
        </root>
        """;

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

final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {

    final var attrA = element.getAttribute("aa");
    System.out.println(attrA); // AA

    final var attrB = element.getAttribute("bb");
    System.out.println(attrB); // BB
}

Attr getAttributeNode (String name)

Retrieves an attribute node by name.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root>
            <child aa="AA" bb="BB" />
        </root>
        """;

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

final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {

    final var attrA = element.getAttributeNode("aa");
    System.out.println(attrA); // aa="AA"

    final var attrB = element.getAttributeNode("bb");
    System.out.println(attrB); // bb="BB"
}

Attr getAttributeNodeNS (String namespaceURI, String localName)

Retrieves an Attr node by local name and namespace URI.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns1="sample1" xmlns:ns2="sample2" >
            <child ns1:aa="AA1" ns2:aa="AA2" />
        </root>
        """;

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

final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {

    final var attrA = element.getAttributeNodeNS("sample1", "aa");
    System.out.println(attrA); // ns1:aa="AA1"

    final var attrB = element.getAttributeNodeNS("sample2", "aa");
    System.out.println(attrB); // ns2:aa="AA2"
}

String getAttributeNS (String namespaceURI, String localName)

Retrieves an attribute value by local name and namespace URI.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns1="sample1" xmlns:ns2="sample2" >
            <child ns1:aa="AA1" ns2:aa="AA2" />
        </root>
        """;

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

final var node = document.getElementsByTagName("child").item(0);
if (node instanceof Element element) {

    final var attrA = element.getAttributeNS("sample1", "aa");
    System.out.println(attrA); // AA1

    final var attrB = element.getAttributeNS("sample2", "aa");
    System.out.println(attrB); // AA2
}

NodeList getElementsByTagName (String name)

Returns a NodeList of all descendant Elements with a given tag name, in document order.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root>
            <child-a/>
            <child-b/>

            <child-c>
                <child-b/>
                <child-b/>
            </child-c>
        </root>
        """;

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

final var root = document.getDocumentElement();

final var nodesA = root.getElementsByTagName("child-a");
System.out.println("-- child-a --");
for (int i = 0; i < nodesA.getLength(); i++) {
    final var item = nodesA.item(i);
    System.out.println("node = " + item + " : parent = " + item.getParentNode());
}

// Result
// ↓
//-- child-a --
//node = [child-a: null] : parent = [root: null]

final var nodesB = root.getElementsByTagName("child-b");
System.out.println("-- child-b --");
for (int i = 0; i < nodesB.getLength(); i++) {
    final var item = nodesB.item(i);
    System.out.println("node = " + item + " : parent = " + item.getParentNode());
}

// Result
// ↓
//-- child-b --
//node = [child-b: null] : parent = [root: null]
//node = [child-b: null] : parent = [child-c: null]
//node = [child-b: null] : parent = [child-c: null]

final var nodesC = root.getElementsByTagName("child-c");
System.out.println("-- child-c --");
for (int i = 0; i < nodesC.getLength(); i++) {
    final var item = nodesC.item(i);
    System.out.println("node = " + item + " : parent = " + item.getParentNode());
}

// Result
// ↓
//-- child-c --
//node = [child-c: null] : parent = [root: null]

NodeList getElementsByTagNameNS (String namespaceURI, String localName)

Returns a NodeList of all the descendant Elements with a given local name and namespace URI in document order.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns="sample">
            <child-a/>
            <child-a/>

            <child-b/>
            <ns:child-b/>
            <ns:child-b/>
        </root>
        """;

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

final var root = document.getDocumentElement();

final var nodesA = root.getElementsByTagName("child-a");
System.out.println("-- child-a --");
for (int i = 0; i < nodesA.getLength(); i++) {
    System.out.println(nodesA.item(i));
}

// Result
// ↓
//-- child-a --
//[child-a: null]
//[child-a: null]

final var nodesB1 = root.getElementsByTagName("child-b");
System.out.println("-- child-b --");
for (int i = 0; i < nodesB1.getLength(); i++) {
    System.out.println(nodesB1.item(i));
}

// Result
// ↓
//-- child-b --
//[child-b: null]

final var nodesB2 = root.getElementsByTagNameNS("sample", "child-b");
System.out.println("-- ns:child-b --");
for (int i = 0; i < nodesB2.getLength(); i++) {
    System.out.println(nodesB2.item(i));
}

// Result
// ↓
//-- ns:child-b --
//[ns:child-b: null]
//[ns:child-b: null]

TypeInfo getSchemaTypeInfo ()

The type information associated with this element.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root>
            <child aa="AA"/>
        </root>
        """;

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

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    System.out.println(element.getSchemaTypeInfo()); // [child: null]

    final var attr = element.getAttributeNode("aa");
    System.out.println(attr.getSchemaTypeInfo()); // aa="AA"
}

String getTagName ()

The name of the element.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root>
            <child/>
        </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.getTagName()); // root

final var child = root.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    System.out.println(element.getTagName()); // child
}

boolean hasAttribute (String name)

Returns true when an attribute with a given name is specified on this element or has a default value, false otherwise.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root>
            <child aa="AA" bb="BB"/>
        </root>
        """;

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

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {

    System.out.println(element.hasAttribute("aa")); // true
    System.out.println(element.hasAttribute("bb")); // true
    System.out.println(element.hasAttribute("cc")); // false
}

boolean hasAttributeNS (String namespaceURI, String localName)

Returns true when an attribute with a given local name and namespace URI is specified on this element or has a default value, false otherwise.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns1="sample1" xmlns:ns2="sample2">
            <child ns1:aa="AA" ns2:bb="BB"/>
        </root>
        """;

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

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {

    System.out.println(element.hasAttributeNS("sample1", "aa")); // true
    System.out.println(element.hasAttributeNS("sample2", "aa")); // false

    System.out.println(element.hasAttributeNS("sample1", "bb")); // false
    System.out.println(element.hasAttributeNS("sample2", "bb")); // true
}

void removeAttribute (String name)

Removes an attribute by name.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root><child aa="AA" bb="BB" /></root>
        """;

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

//<root>
//    <child aa="AA" bb="BB"/>
//</root>
printDocument(document);

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    element.removeAttribute("aa");
}

//<root>
//    <child bb="BB"/>
//</root>
printDocument(document);

Attr removeAttributeNode (Attr oldAttr)

Removes the specified attribute node.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root><child aa="AA" bb="BB" /></root>
        """;

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

//<root>
//    <child aa="AA" bb="BB"/>
//</root>
printDocument(document);

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    final var oldAttr = element.getAttributeNode("aa");
    System.out.println(oldAttr); // aa="AA"

    final var ret = element.removeAttributeNode(oldAttr);
    System.out.println(ret); // aa="AA"
}

//<root>
//    <child bb="BB"/>
//</root>
printDocument(document);

void removeAttributeNS (String namespaceURI, String localName)

Removes an attribute by local name and namespace URI.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns1="sample1" xmlns:ns2="sample2" ><child ns1:aa="AA1" ns2:aa="AA2" /></root>
        """;

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

//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
//    <child ns1:aa="AA1" ns2:aa="AA2"/>
//</root>
printDocument(document);

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    element.removeAttributeNS("sample1", "aa");
}

//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
//    <child ns2:aa="AA2"/>
//</root>
printDocument(document);

void setAttribute (String name, String value)

Adds a new attribute.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root><child/></root>
        """;

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

//<root>
//    <child/>
//</root>
printDocument(document);

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    element.setAttribute("aa", "AA");
    element.setAttribute("bb", "BB");
    element.setAttribute("cc", "CC");
}

//<root>
//    <child aa="AA" bb="BB" cc="CC"/>
//</root>
printDocument(document);

Attr setAttributeNode (Attr newAttr)

Adds a new attribute node.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root><child/></root>
        """;

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

//<root>
//    <child/>
//</root>
printDocument(document);

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    final var attr1 = document.createAttribute("aa");
    attr1.setValue("AA");

    final var ret1 = element.setAttributeNode(attr1);
    System.out.println(ret1); // null

    //<root>
    //    <child aa="AA"/>
    //</root>
    printDocument(document);

    final var attr2 = document.createAttribute("bb");
    attr2.setValue("BB-1");

    final var ret2 = element.setAttributeNode(attr2);
    System.out.println(ret2); // null

    //<root>
    //    <child aa="AA" bb="BB-1"/>
    //</root>
    printDocument(document);

    final var attr3 = document.createAttribute("bb");
    attr3.setValue("BB-2");

    final var ret3 = element.setAttributeNode(attr3);
    System.out.println(ret3); // bb="BB-1"

    //<root>
    //    <child aa="AA" bb="BB-2"/>
    //</root>
    printDocument(document);
}

Attr setAttributeNodeNS (Attr newAttr)

Adds a new attribute.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns1="sample1" xmlns:ns2="sample2"><child/></root>
        """;

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

//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
//    <child/>
//</root>
printDocument(document);

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {

    final var attr1 = document.createAttributeNS("sample1", "ns1:aa");
    attr1.setValue("AA-1");

    final var ret1 = element.setAttributeNode(attr1);
    System.out.println(ret1); // null

    //<root xmlns:ns1="sample1" xmlns:ns2="sample2">
    //    <child ns1:aa="AA-1"/>
    //</root>
    printDocument(document);

    final var attr2 = document.createAttributeNS("sample1", "ns1:aa");
    attr2.setValue("AA-2");

    final var ret2 = element.setAttributeNode(attr2);
    System.out.println(ret2); // ns1:aa="AA-1"

    //<root xmlns:ns1="sample1" xmlns:ns2="sample2">
    //    <child ns1:aa="AA-2"/>
    //</root>
    printDocument(document);

    final var attr3 = document.createAttributeNS("sample2", "ns2:aa");
    attr3.setValue("AA-3");

    final var ret3 = element.setAttributeNode(attr3);
    System.out.println(ret3); // null

    //<root xmlns:ns1="sample1" xmlns:ns2="sample2">
    //    <child ns1:aa="AA-2" ns2:aa="AA-3"/>
    //</root>
    printDocument(document);
}

void setAttributeNS (String namespaceURI, String qualifiedName, String value)

Adds a new attribute.

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns1="sample1" xmlns:ns2="sample2"><child/></root>
        """;

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

//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
//    <child/>
//</root>
printDocument(document);

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    element.setAttributeNS("sample1", "ns1:aa", "AA-1");
    element.setAttributeNS("sample2", "ns2:aa", "AA-2");
}

//<root xmlns:ns1="sample1" xmlns:ns2="sample2">
//    <child ns1:aa="AA-1" ns2:aa="AA-2"/>
//</root>
printDocument(document);

void setIdAttribute (String name, boolean isId)

If the parameter isId is true, this method declares the specified attribute to be a user-determined ID attribute .

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root><child id-a="ID-A"/></root>
        """;

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

//<root>
//    <child id-a="ID-A"/>
//</root>
printDocument(document);

final var before = document.getElementById("ID-A");
System.out.println(before); // null

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    element.setIdAttribute("id-a", true);
}

final var after = document.getElementById("ID-A");
System.out.println(after); // [child: null]

//<root>
//    <child id-a="ID-A"/>
//</root>
printDocument(document);

void setIdAttributeNode (Attr idAttr, boolean isId)

If the parameter isId is true, this method declares the specified attribute to be a user-determined ID attribute .

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root><child id-a="ID-A"/></root>
        """;

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

//<root>
//    <child id-a="ID-A"/>
//</root>
printDocument(document);

final var before = document.getElementById("ID-A");
System.out.println(before); // null

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    final var attr = element.getAttributeNode("id-a");
    System.out.println(attr); // id-a="ID-A"

    element.setIdAttributeNode(attr, true);
}

final var after = document.getElementById("ID-A");
System.out.println(after); // [child: null]

//<root>
//    <child id-a="ID-A"/>
//</root>
printDocument(document);

void setIdAttributeNS (String namespaceURI, String localName, boolean isId)

If the parameter isId is true, this method declares the specified attribute to be a user-determined ID attribute .

Element (Java SE 22 & JDK 22) 
final var xml = """
        <root xmlns:ns="sample"><child ns:id-a="ID-A"/></root>
        """;

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

//<root xmlns:ns="sample">
//    <child ns:id-a="ID-A"/>
//</root>
printDocument(document);

final var before = document.getElementById("ID-A");
System.out.println(before); // null

final var child = document.getElementsByTagName("child").item(0);
if (child instanceof Element element) {
    element.setIdAttributeNS("sample", "id-a", true);
}

final var after = document.getElementById("ID-A");
System.out.println(after); // [child: null]

//<root xmlns:ns="sample">
//    <child ns:id-a="ID-A"/>
//</root>
printDocument(document);

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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