Empty lines appear after the element is removed from the xml file

Some elements have been added to the xml file through the add method. But why does the xml file leave a blank line after deleting an element, and how to get rid of it?
The main function is:

@Test
    public void test() {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        OperateXml operateXml = new OperateXml();
        try {
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document document = builder.parse(new ClassPathResource("chunkInfo/chunk.xml").getFile());
// operateXml.add(document);
            operateXml.deleteNodeById(document,"id_5");
            operateXml.saveDocument(document, new ClassPathResource("chunkInfo/chunk.xml").getFile());
} catch (Exception e) {
            System.out.println(e);
        }
}

The save function is:

public static void saveDocument(Document document, File xmlFile) {
        TransformerFactory tff = TransformerFactory.newInstance();
        try {
            Transformer tf = tff.newTransformer();
            tf.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "chunk.dtd");
            tf.setOutputProperty(OutputKeys.INDENT, "yes");
            tf.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
            tf.transform(new DOMSource(document), new StreamResult(xmlFile));
        } catch (TransformerException e) {
            e.printStackTrace();
        }
    }

Before deleting the element, the xml file is：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE save SYSTEM "chunk.dtd">
<save>
    <chunk id="id_1">
    <name>test_6</name>
    <type>log</type>
    <item>2,3,4,5</item>
  </chunk>
    <chunk id="id_3">
    <name>test_6</name>
    <type>log</type>
    <item>2,3,4,5</item>
  </chunk>
    <chunk id="id_4">
    <name>test_6</name>
    <type>log</type>
    <item>2,3,4,5</item>
  </chunk>
<chunk id="id_5">
    <name>test_7</name>
    <type>log</type>
    <item>2,3,4,5</item>
  </chunk>
</save>

After deleting the element (id="id_5"), the xml file is：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE save SYSTEM "chunk.dtd">
<save>
    <chunk id="id_1">
    <name>test_6</name>
    <type>log</type>
    <item>2,3,4,5</item>
  </chunk>
    <chunk id="id_3">
    <name>test_6</name>
    <type>log</type>
    <item>2,3,4,5</item>
  </chunk>
    <chunk id="id_4">
    <name>test_6</name>
    <type>log</type>
    <item>2,3,4,5</item>
  </chunk>

</save>

>Solution :

The reason is likely because there are invisible [text] nodes between your elements (in the example below ‘\n’ is a newline and ‘\t’ is a tab indent):

<save>[text '\n
\t']<chunk id="id_1">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t\t']</chunk>[text \n
\t']<chunk id="id_3">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t']<chunk id="id_4">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t']<chunk id="id_5">[text '\n
\t\t']<name>test_7</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n']
</save>

When you remove everything under <chunk id="id_5"> it leaves the [text] nodes around it.

<save>[text '\n
\t']<chunk id="id_1">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t\t']</chunk>[text \n
\t']<chunk id="id_3">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t']<chunk id="id_4">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t'][..where chunk used to be..][text '\n']
</save>

One option to resolve this would be to re-format the document.

Another is to get the reference to the element you want to delete, check its preceding sibling node, and if it’s a blank text node then remove it as well.