How to add DTD in XML file to remove whitespace text content during the SAX parsing process?

Sometimes when you are using the SAX parser to process an XML file in a print pretty format, the characters() handler method will be called for those extra whitespace text contents.

For example, look at the following print pretty XML file, User.xml:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- Copyright (c) 2017 FYIcenter.com -->
<User>
    <ID>101</ID>
    <BirthDate>1970-01-01+00:01</BirthDate>
    <Name>Frank Y. Ivy</Name>
    <Sex>  Male</Sex>
</User>

If you run the example program, SaxXmlParser.java, presented in the previous tutorial with User.xml, you will see that characters() got called with those extra whitespaces:

>\fyicenter\jdk-1.8.0\bin\java SaxXmlParser User.xml

Parser class: com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl

.User(
    )
..ID(101)(
    )
..BirthDate(1970-01-01+00:01)(
    )
..Name(Frank Y. Ivy)(
    )
..Sex(  Male)(
)

One way to fix the problem is to add the DTD section in XML file to provide the XML file structure to help the SAX parser:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- Copyright (c) 2017 FYIcenter.com -->
<!DOCTYPE User [
   <!ELEMENT User (ID, BirthDate, Name, Sex)>
   <!ELEMENT ID (#PCDATA)>
   <!ELEMENT BirthDate (#PCDATA)>
   <!ELEMENT Name (#PCDATA)>
   <!ELEMENT Sex (#PCDATA)>
]>

<User>
    <ID>101</ID>
    <BirthDate>1970-01-01+00:01</BirthDate>
    <Name>Frank Y. Ivy</Name>
    <Sex>  Male</Sex>
</User>

If you run the example program, SaxXmlParser.java, presented in the previous tutorial with UserDTD.xml, you will not see any whitespaces text content:

>\fyicenter\jdk-1.8.0\bin\java SaxXmlParser UserDTD.xml

Parser class: com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl

.User
..ID(101)
..BirthDate(1970-01-01+00:01)
..Name(Frank Y. Ivy)
..Sex(  Male)

⇒ SaxXmlWhitespace.java - ignorableWhitespace() Event Handler

⇐ SaxXmlParser.java - SAX XML Parser Example

⇑ Using XML SAX API with Apache Xerces

⇑⇑ FAQ for Apache Xerces XML Parser