10 common XML interview questions for Java programmers

XML interview questions include XSLT, XPATH, XQuery and other XML technologies used to transform XML files, as well as XML basics such as DTDS or schemas.

This article looks at 10 common XML interview questions. Most of these questions are asked in Java interviews, but they are also useful in programming interviews in C, C++, Scala, or other languages. XML is not dependent on other programming languages and, like SQL, is one of the skills programmers need, so it makes sense to prepare some XML questions before any technical job interview.

XML interview questions

Below is a list of interview questions I often ask about XML technology. These issues are not difficult but cover some important areas of XML technology, such as DTDS, XML schemas, XSLT transformations, XPATH retrieval, XML binding, XML parsers, and the basics of XML, such as namespaces, validations, attributes, elements, and so on.

Question 1: what is XML?

A: XML is the Extensible Markup language, which you can extend to suit your needs. Easily defined in XML. Books> , < Orders> While other markup languages, such as HTML, must use predefined tags, such as < P> Instead of using user-defined tags. Standardize XML structures using DTDS and XML schemas. XML is primarily used for data transfer from one system to another, such as the client and server sides of enterprise applications.

Question 2: what is the difference between a DTD and an XML Schema?

A: DTDS differ from XML Schema in the following ways: DTDS are not written in XML and XML Schema is itself an XML file, which means that existing XML tools such as XML parsers can be used to process XML schemas. Moreover, XML Schema is designed after DTD, which provides more types to map different data types of XML files. A DTD, or Document Type definition, is the traditional way to define the structure of an XML file.

Question 3: what is XPath?

A: XPath is an XML technology for retrieving elements from an XML document. XML documents are structured, so XPath can locate and retrieve elements, attributes, or values from XML files. XPath is similar to SQL in terms of data retrieval, but it has its own syntax and rules. Learn more about how to use XPath to retrieve data from an XML document.

Question 4: what is XSLT?

A: XSLT is also a common XML technique for converting an XML file into another XML, HTML, or other format. XSLT defines its own syntax, functions, and operators for transforming XML files in detail. The transformation is usually done by an XSLT engine, which reads the instructions for an XML stylesheet or XSL file written in the XSLT syntax. XSLT makes heavy use of recursion to perform transformations. A common use of XSLT is to display the data in an XML file as an HTML page. XSLT also makes it easy to transform one XML file into another.
Question 5: what are XML elements and attributes

A: an example is best. The following is a simple XML snippet.

<Orders>
    <Order id="123">
        <Symbol>6758.T</Symbol>
        <Price>2300</Price>
    <Order>
<Orders>

In the example, the id is an attribute of the element, and the other elements have no attributes.

Question 6: what is well-formed XML

A: this question often comes up in phone interviews. A well-formed XML means that the XML document is syntactically correct, such as it has a root element, all open tags are properly closed, attribute values must be quoted, and so on. If an XML is not well-formed, it may not be processed and parsed correctly by various XML parsers.

Question 7: what is an XML namespace? Why is it important?

Answer: the XML namespace is similar to the Java package and is used to avoid conflicting tags with different source names. The XML namespace is defined at the top of the XML document using the XMLNS attribute, with the syntax XMLNS :prefix='URI'. Prefix is used with the actual tag in the XML document. The following example is for the use of XML namespaces.

<root xmlns:inst="http://instruments.com/inst"
    <inst:phone>
        <inst:number>837363223</inst:number>
    </inst:phone>
</root>

Question 8: what is the difference between a DOM and a SAX parser

A: this is another frequently asked question, not only in XML interviews, but also in Java interviews. The main difference between DOM and SAX parsers is the way they parse XML documents. With DOM parsing, XML documents are loaded into memory in a tree structure, while SAX is an event-driven parser. A more detailed answer to this question looks at the differences between DOM and SAX parsers.

Question 9: what is XML CDATA

A: this problem is simple and important, but many programmers don't know much about it. CDATA is character data that has special instructions that are parsed by the XML parser. An XML parser parses all the text in an XML document, such as < Name> This is name of person< / name> , the value of the tag is also parsed because the tag value may also contain XML tags, such as < Name> < Firstname> First Name< / firstname> < / name> . The CDATA section is not parsed by the XML parser. The CDATA section begins with"

Question 10: what is the XML data binding for Java

Answer: Java's XML binding refers to creating classes and objects from XML files and modifying XML documents using the Java programming language. A Java API for XML binding, JAXB provides a convenient way to bind XML documents and Java objects. Another alternative to XML binding is to use open source libraries, such as XML Beans. One of the biggest advantages of XML binding in Java is the ability to create and modify XML documents using Java programming capabilities.

The above XML interview questions were collected from many programmers, but they are useful for everyone who USES XML technology. Due to the platform-independent nature of XML, XML technologies such as XPath, XSLT and XQuery are increasingly important, and XML is widely used for cross-platform data transmission. Despite its shortcomings such as redundancy and large document size, XML plays a big role in transferring data between web services and systems where bandwidth and rate are secondary considerations.