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JDOM Example : Reading and Parsing XML with SAX parser in Java

XML parsing with JDOM parser
JDOM is an open source library which allow XML parsing and reading in Java program. JDOM is designed by using Java programming technique and customized for Java programmers, so that Java programmer with  very little knowledge of XML documents can use JDOM to read XML files. Unlike DOM Parser of Java API , which uses Factory design pattern to create instance of parser e.g DocumentBuilderFactory and DocumentBuilder, as seen in our last example of parsing XML documents in Java, JDOM uses new() operator to create its parser instances. In fact JDOM is very easy to understand and most of the time its self explanatory. While trying this Java program to parse XML file, you can explore JDOM API. JDOM API also allows to use XPATH expression to query XML documents with package org.jdom2.xpath. In next section we will see complete code example of How to read an XML file using JDOM parser in Java program.

How to Search Element in Java Array with Example

find an index of the object in Array
While programming in Java, many times we need to check if a String array contains a particular String or an int array contains a number or not. Though array is an object in Java but it does not provide any convenient method to perform these kinds of operations. Sometimes you even need an index of an item stored in Array, unfortunately, Java API does not provide any direct method. Thanks to Open Source Apache Commons provides a utility class called ArrayUtils which allows you to check for an Item in Array, find its index in the array, find its lastIndex in Array and perform several other common operations. In fact, ArrayUtils has overloaded methods for different kinds of Array e.g. String, int, float, double, Object, etc, which makes this kind of programming task trivial. In this article, we will see an Apache commons example of How to use ArrayUtils class to search an item in Array and find its index.

Difference between Serializable vs Externalizable in Java - Interview Question

Serializable vs Externalizable
What is the difference between Serializable and Externalizable in Java is famous core Java interview questions and for some of them its one of those difficult Java question, which no one wants to see in Java interview. I was in that category until I explored How Serialization works in Java and find out more about the Serialization process. What makes Serialization questions tricky is, Serialization as a persistence mechanism is not very popular. Many programmers prefer databases, memory-mapped files, or simple text files over Serialization. But Serialization has a distinguished advantage over these mechanisms.

How to iterate over HashSet in Java - loop or traverse Example

Iterating over HashSet in Java
Java program to Iterate over HashSet in Java with ExampleIn our last Java collection tutorial, we have seen How to iterate over ArrayList in Java and in this tutorial we will see How to iterate over HashSet in Java. There are two ways to iterate, loop or traverse over HashSet in Java, first using advanced for-each loop added on Java 5 and second using Iterator which is a more conventional way of iterating over HashSet in Java. Now questions are When should you use for loop and when Iterator is an appropriate option. Well I usually use for loop If I only read from HashSet and doesn't remove any element, while Iterator is preferred approach. You should not remove elements from HashSet while iterating over it in for loop, Use Iterator to do that.

How to convert Hexadecimal to Decimal, Binary and Octal in Java program - Example

Hexadecimal to decimal and binary conversion in Java
This Java program will convert Hexadecimal number to decimal, binary and Octal in Java programming language using JDK standard API methods. For beginners hexadecimal is base 16 number, while decimal is base 10, Octal is base 8, and binary is base 2 numbers in Number systems. Binary only contains 0 and 1 bits, octal contains 0 to 7, decimal contains 0 to 9 and Hexadecimal contains 0-9,A,B,C,D,E,F where F represent 15. Thankfully Java library provides a convenient method to convert any integer from one number system to another. In our last article we have seen How to convert decimal numbers to binary in Java and in this article we will convert Hexadecimal numbers to binary, octal, and decimal numbers.

How to convert ArrayList to String in Java - Spring Example

Some time we need to convert ArrayList to String in Java programming language in order to pass that String to stored procedure, any method or any other program. Unfortunately Java collection framework doesn't provide any direct utility method to convert ArrayList to String in Java. But Spring framework which is famous for dependency Injection and its IOC container also provides API with common utilities like method to convert Collection to String in Java. You can convert ArrayList to String using Spring Framework's StringUtils class. StringUtils class provide three methods to convert any collection e.g. ArrayList to String in Java, as shown below:

20 EJB 3.0 Interview Questions and Answers - Java J2EE

EJB interview questions are core part of any Java J2EE interview. As EJB forms business layer for modern J2EE enterprise application, Good knowledge of EJB is expected from J2EE programmer. Purpose of these EJB interview questions is to give an Idea about what kind of questions you can expect on J2EE and EJB interviews. EJB was always tough for Java programmer because of heavy weight architecture comprised with many interfaces e.g. home interface, remote interface, local interface, bean class etc. It take too much time and knowledge to implement and use EJB in your Java web and enterprise application forget about challenges posed by application servers like WebLogic or IBM WebSphere.

Java Program to Read a File in Java - Windows UNIX Example

Java provides java.io  package in JDK API for reading File in Java from File system e.g. C:\ or D:\ drive in Windows or any other directory in UNIX. First, you can use FileInputStream to open a file for reading. FileInputStream takes a String parameter which is a path for the file you want to read. Be careful while specifying File path as path separator is different on Window and UNIX. Windows uses back slash while UNIX uses forward slash as a path separator. By the way, Java supports forward slash in Windows, It means if use forward slash your program will work on both Windows and UNIX. Alternatively, you can also get PATH separator from System property path.separator. In this Java tutorial, we will code example of How to read File in Java.