Interview Questions.

Top 100+ Java Xml Interview Questions And Answers

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Top 100+ Java Xml Interview Questions And Answers

Question 1. What Xml Stands For?

Answer :

XML stands for Extensible Markup Language.

Question 2. What Are The Advantages Of Using Xml?

Answer :

Following are the blessings that XML gives:

Technology agnostic - Being simple text, XML is technology impartial. It may be utilized by any technology for statistics storage and transmission cause.
Human readable- XML makes use of easy text format. It is human readable and comprehensible.
Extensible - in XML, custom tags may be created and used very without problems.
Allow Validation - Using XSD, DTD and XML structure can be confirmed easily.
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Question 3. What Are The Disadvantages Of Using Xml?

Answer :

Following are the disadvantages of XML utilization:

Redundant Syntax - Normally XML record carries lot of repeatitive terms.
Verbose-Being a verbose language, XML report length will increase the transmission and garage expenses.
Question 4. What Is Xml Parsing?

Answer :

Parsing XML refers to going thru XML document to get entry to statistics or to regulate information in one or other way.

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Question 5. What Is Xml Parser?

Answer :

XML Parser offers manner how to get entry to or adjust statistics found in an XML report. Java provides a couple of alternatives to parse XML file.

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Question 6. Name Some Of The Parsers Which Are Commonly Used To Parse Xml Documents?

Answer :

Following are various forms of parsers that are normally used to parse XML documents:

Dom Parser - Parses the report by way of loading the complete contents of the document and growing its entire hiearchical tree in memory.
SAX Parser - Parses the record on occasion based totally triggers. Does no longer load the complete report into the memory.
JDOM Parser - Parses the report in comparable fashion to DOM parser but in extra less difficult manner.
StAX Parser - Parses the record in comparable fashion to SAX parser but in extra green manner.
XPath Parser - Parses the XML based totally on expression and is used substantially in conjuction with XSLT.
DOM4J Parser - A java library to parse XML, XPath and XSLT the usage of Java Collections Framework , provides help for DOM, SAX and JAXP.
Question 7. What Dom Stands For?

Answer :

DOM stands for Document Object Model.

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Question 8. What Is Dom?

Answer :

DOM stands for Document Object Model and it's miles an reliable advice of the World Wide Web Consortium (W3C). It defines an interface that permits programs to access and replace the style, shape,and contents of XML files. XML parsers that guide the DOM put in force that interface.

Question nine. When To Use A Dom Parser?

Answer :

You must use a DOM parser when:

You want to understand a lot approximately the shape of a record
You need to transport elements of the report around (you would possibly need to sort positive factors, for example)
You want to apply the information in the document extra than as soon as
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Question 10. What Dom Parser Returns?

Answer :

When you parse an XML file with a DOM parser, you get again a tree structure that contains all the factors of your file. The DOM provides a spread of functions you may use to study the contents and structure of the file.

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Question eleven. What Are The Advantages Of Dom Parsing?

Answer :

The DOM is a commonplace interface for manipulating file structures. One of its design dreams is that Java code written for one DOM-compliant parser must run on every other DOM-compliant parser without adjustments.

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Question 12. What Are The Key Components/interfaces Of Dom Parsing?Call Some Of The Important Dom Parsing Methods.?

Answer :

When you are running with the DOM, there are several techniques you'll use frequently:

Document.GetDocumentElement() - Returns the basis detail of the file.
Node.GetFirstChild() - Returns the primary baby of a given Node.
Node.GetLastChild() - Returns the last baby of a given Node.
Node.GetNextSibling() - These strategies return the next sibling of a given Node.
Node.GetPreviousSibling() - These techniques go back the preceding sibling of a given Node.
Node.GetAttribute(attrName) - For a given Node, returns the characteristic with the asked name.
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Question 13. Can We Create An Xml Document Using Dom Parser?

Answer :

Yes! Using DOM parser, we will parse, adjust or create a XML document.

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Question 14. What Sax Stands For?

Answer :

SAX stands for Simple API for XML.

Question 15. What Is A Sax Parser?

Answer :

SAX Parser is an occasion-based totally parser for xml documents.

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Question 16. How A Sax Parser Works?

Answer :

SAX (the Simple API for XML) is an occasion-primarily based parser for xml documents.Unlike a DOM parser, a SAX parser creates no parse tree. SAX is a streaming interface for XML, because of this that programs the use of SAX get hold of event notifications about the XML record being processed an detail, and attribute, at a time in sequential order starting on the pinnacle of the record, and ending with the final of the ROOT element.

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Question 17. When To Use A Sax Parser?

Answer :

You have to use a SAX parser when:

You can procedure the XML document in a linear fashion from the pinnacle down
The record isn't always deeply nested
You are processing a completely massive XML record whose DOM tree might eat an excessive amount of reminiscence.Typical DOM implementations use ten bytes of memory to represent one byte of XML
The trouble to be solved includes handiest a part of the XML file
Data is to be had as soon as it is visible by using the parser, so SAX works properly for an XML record that arrives over a circulate
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Question 18. What Are The Disadvantages Of Sax Parsing?

Answer :

We don't have any random get entry to to an XML document on the grounds that it is processed in a forward-best manner
If you need to hold song of information the parser has seen or trade the order of items, you ought to write the code and shop the records on your own
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Question 19. Name Some Of The Important Sax Parsing Methods?

Answer :

ContentHandler Interface specifies the callback strategies that the SAX parser uses to notify an application application of the components of the XML report that it has seen.

Void startDocument() - Called at the beginning of a record.
Void endDocument() - Called at the stop of a report.
Void startElement(String uri, String localName, String qName, Attributes atts) - Called at the beginning of an detail.
Void endElement(String uri, String localName,String qName) - Called at the quit of an element.
Void characters(char[] ch, int start, int period) - Called while individual information is encountered.
Void ignorableWhitespace( char[] ch, int start, int duration) - Called while a DTD is present and ignorable whitespace is encountered.
Void processingInstruction(String target, String records) - Called while a processing preparation is diagnosed.
Void setDocumentLocator(Locator locator)) - Provides a Locator that may be used to become aware of positions within the record.
Void skippedEntity(String call) - Called when an unresolved entity is encountered.
Void startPrefixMapping(String prefix, String uri) - Called whilst a brand new namespace mapping is described.
Void endPrefixMapping(String prefix) - Called while a namespace definition ends its scope.
Question 20. Name Some Methods For Processing The Attributes Connected To An Element In Sax Parsing?

Answer :

Attributes Interface specifies techniques for processing the attributes linked to an element.

Int getLength() - Returns range of attributes.
String getQName(int index)
String getValue(int index)
String getValue(String qname)
 

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Question 21. Can We Create An Xml Document Using Sax Parser?

Answer :

No! Using SAX parser, we can only parse or modify a XML report.

Question 22. What Is Jdom Parser?

Answer :

JDOM is an open source, java primarily based library to parse XML file and it's miles commonly java developer friendly API.

Question 23. What Are The Benefits Of Jdom Parser?

Answer :

It is java optimized, it makes use of java series like List and Arrays. It works with DOM and SAX APIs and combines the best of the two. It is of low reminiscence footprint and is nearly as rapid as SAX.

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Question 24. When To Use A Jdom Parser?

Answer :

You should use a JDOM parser whilst:

You want to know loads approximately the structure of a document.
You want to transport components of the file round (you might want to sort sure factors, as an instance).
You want to apply the records inside the file more than as soon as.
You are a java developer and want to leverage java optimized parsing of XML.
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Question 25. What Are The Advantages Of Jdom Parser?

Answer :

When you parse an XML document with a JDOM parser, you get the ability to get again a tree structure that incorporates all the factors of your report without impacting the memory footprint of the software. The JDOM affords a selection of software features you could use to examine the contents and structure of the document in case file is properly established and its structure is understood.

JDOM offers java developers flexibility and smooth maintainablity of xml parsing code. It is mild weight and short API.

Question 26. Name Some Of The Important Jdom Classes?

Answer :

The JDOM defines numerous Java lessons. Here are the maximum not unusual classes :

Document - Represents the entire XML report. A Document object is regularly called a DOM tree.
Element - Represents an XML detail. Element object has methods to govern its child factors,its text, attributes and namespaces.
Attribute Represents an attribute of an detail. Attribute has approach to get and set the fee of characteristic. It has parent and characteristic kind.
Text Represents the text of XML tag.
Comment Represents the remarks in a XML report.
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Question 27. Name Some Of The Important Jdom Methods?

Answer :

When you are working with the JDOM, there are several techniques you'll use regularly:

SAXBuilder.Construct(xmlSource) - Build the JDOM record from the xml supply.
Document.GetRootElement() - Get the basis element of the XML.
Element.GetName() - Get the call of the XML node.
Element.GetChildren() - Get all of the direct infant nodes of an element.
Node.GetChildren(Name) - Get all of the direct child nodes with a given name.
Node.GetChild(Name) - Get first toddler node with given call.
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Question 28. Can We Create An Xml Document Using Jdom Parser?

Answer :

Yes! Using JDOM parser, we can parse, alter and create a XML record.

Question 29. What Is A Stax Parser?

Answer :

StAX is a JAVA based totally API to parse XML record in a comparable manner as SAX parser does however StAX is a PULL API wherein as SAX is a PUSH API. It way in case of StAX parser, client application need to invite StAX parser to get records from XML on every occasion it desires but in case of SAX parser, client utility is required to get information whilst SAX parser notifies the purchaser application that records is available.

Question 30. Can We Create An Xml Document Using Stax Parser?

Answer :

Yes! Using StAX parser, we will parse, regulate and create a XML file.

Question 31. Is Stax Parser A Pull Api?

Answer :

Yes! StAX is a PULL API.

Question 32. When You Should Use A Stax Parser?

Answer :

You have to use a StAX parser while:

You can system the XML record in a linear style from the pinnacle down.
The report isn't always deeply nested.
You are processing a totally huge XML report whose DOM tree might consume too much memory. Typical DOM implementations use ten bytes of reminiscence to symbolize one byte of XML.
The problem to be solved includes best part of the XML file.
Data is to be had as quickly as it's miles visible by way of the parser, so StAX works properly for an XML file that arrives over a circulation.
Question 33. What Are The Disadvantages Of Stax Parser?

Answer :

We have no random get right of entry to to an XML record due to the fact that it's far processed in a forward-only manner
If you need to hold song of information the parser has visible or trade the order of gadgets, you ought to write the code and keep the records to your very own.
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Question 34. Explain Xmleventreader Class Of Stax Parser?

Answer :

This elegance offer iterator of occasions which can be used to iterate over events as they arise whilst parsing the XML record.

StartElement asStartElement() - used to retrieve value and attributes of element.
EndElement asEndElement() - referred to as on the cease of a element.
Characters asCharacters() - can be used to acquire characters any such CDATA, whitespace etc.
Question 35. Explain Xmleventwriter Class Of Stax Parser?

Answer :

This interface specifies methods for growing an event.

Add(Event event) - Add occasion containing factors to XML.
Question 36. Explain Xmlstreamreader Class Of Stax Parser?

Answer :

This elegance offer iterator of occasions which can be used to iterate over occasions as they occur while parsing the XML report

int subsequent() - used to retrieve next event.
Boolean hasNext() - used to test in addition activities exists or not
String getText() - used to get text of an element
String getLocalName() - used to get name of an detail
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Question 37. Explain Xmlstreamwriter Class Of Stax Parser?

Answer :

This interface specifies methods for developing an event:

writeStartElement(String localName) - Add begin detail of given name.
WriteEndElement(String localName) - Add quit element of given name.
WriteAttribute(String localName, String cost) - Write characteristic to an detail.
Question 38. What Is Xpath?

Answer :

The XPath is an respectable recommendation of the World Wide Web Consortium (W3C). It defines a language to locate information in an XML report. It is used to traverse elements and attributes of an XML document. XPath offers diverse sort of expressions which may be used to investigate relevant records from the XML document.

Question 39. What Are The Key Components Of Xpath?

Answer :

Following are the key additives of XPath:

Structure Definitions - XPath defines the elements of an XML report like detail, characteristic, text, namespace, processing-education, remark, and record nodes.
Path Expressions XPath offers powerful path expressions select nodes or listing of nodes in XML documents.
Standard FunctionsXPath provides a wealthy library of widespread functions for manipulation of string values, numeric values, date and time evaluation, node and QName manipulation, series manipulation, Boolean values and many others.
Major part of XSLTXPath is one of the foremost element in XSLT widespread and is have to have expertise a good way to paintings with XSLT documents.
W3C recommendationXPath is bureaucratic advice of World Wide Web Consortium (W3C).
Question forty. Can We Create An Xml Document Using Dom4j Parser?

Answer :

Yes! Using DOM4J parser, we are able to parse, regulate and create a XML record.

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Question 41. Name Some Of The Important Dom4j Methods?

Answer :

When you are running with the DOM4J, there are several strategies you'll use frequently:

SAXReader.Read(xmlSource)() - Build the DOM4J file from the xml source.
Document.GetRootElement() - Get the foundation detail of the XML.
Element.Node(index) - Get the XML node at unique index inside the element.
Element.Attributes() - Get all of the attributes of an detail.
Node.ValueOf(@Name) - Get the value of an attribute with given name of the detail.
Question forty two. When Are The Advantages Of Using A Dom4j Parser?

Answer :

DOM4J offers java builders flexibility and clean maintainablity of xml parsing code. It is mild weight and brief API.

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Question forty three. Name Some Of The Important Dom4j Classes?

Answer :

The DOM4J defines several Java classes.

Here are the most common training:

Document - Represents the complete XML file. A Document item is frequently called a DOM tree.
Element - Represents an XML element. Element object has strategies to control its toddler factors,its text, attributes and namespaces.
Attribute Represents an attribute of an detail. Attribute has technique to get and set the price of attribute. It has figure and characteristic type.
Node Represents Element, Attribute or ProcessingInstruction
Question forty four. When Are The Benefits Of Using A Dom4j Parser?

Answer :

When you parse an XML file with a DOM4J parser, you get the ability to get lower back a tree shape that consists of all of the factors of your report with out impacting the memory footprint of the utility. The DOM4J offers a ramification of utility features you could use to observe the contents and shape of the file in case file is well dependent and its shape is thought. DOM4J uses XPath expression to navigate via the XML record.

Question forty five. When To Use A Dom4j Parser?

Answer :

You ought to use a DOM4J parser whilst:

You need to understand loads about the structure of a file
You need to transport parts of the record round (you might need to type certain elements, as an example)
You want to use the facts within the file more than once
You are a java developer and want to leverage java optimized parsing of XML.
Question forty six. What Is Dom4j Parser?

Answer :

DOM4J is an open source, java based library to parse XML file and it's far exceptionally bendy, excessive-overall performance, and reminiscence-green API. It is java optimized, it uses java collection like List and Arrays. It works with DOM, SAX, XPath and XSLT. It can parse large XML report with very low memory footprint.

Question 47. Can We Create An Xml Document Using Xpath Parser?

Answer :

No! XPath parser is used to to navigate XML Document most effective. It is better to apply DOM parser for creating XML.

Question 48. What Is Path Expression In Xpath?

Answer :

XPath uses a direction expression to choose node or list of nodes from an xml file. Following is the listing of beneficial paths and expression to pick any node/ list of nodes from an xml report.

Expressions:

node-call: Select all nodes with the given name "nodename"
/: Selection begins from the root node
//: Selection starts offevolved from the modern-day node that fit the selection
.: Selects the present day node
..: Selects the figure of the cutting-edge node
@: Selects attributes
pupil: Example − Selects all nodes with the name "scholar"
class/student:  Example: Selects all scholar factors which can be kids of class
//scholar: Selects all pupil factors regardless of where they're in the report




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