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  Core Java
  
  Java is a third generation Programming Language which provide first time API for internet application

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  Advanced Java
  
  SWING, NETWORKING JSP, Servlets, etc

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  SERVLET
  
  A Servlet is a Java programming language class used to extend the capabilities of servers that host applications accessed via a request-response programming model

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  JSP
  
  Java server pages (JSP) is based on java languages and used to develop dynamic web pages JSP was developed by Sun Microsystems to allow server side development.

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  EJB
  
  An enterprise bean is a server-side component that encapsulates the business logic of an application. It written in java so, it is called enterprise java beans.

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  Struts
  
  Struts1.3 is a Frameworks which is an implementation of MVC-2 at server side. Struts1.3 have many advantages over the standard servlet and JSP API alone.

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  HIBERNATE
  
  Hibernate is a java package that makes it easy to work with relational database. Hibernate is an object-relational mapping...

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  SPRING
  
  Spring Framework is a lightweight open source application framework that provide facility to develop enterprise application in java platform.

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  JSF
  
  JSF stands for Java Server Faces. JSF has set of pre-assembled User Interface (UI).

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  Java FAQS
  
  More than thousands of questions with answers links are here....

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  JDBC
  
  Java database connectivity is the API which defines how the client may access the database.

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  J2ME
  
  J2ME (Java 2 Micro Edition) is a feature that allows the device to run small, user-installable software applications written especially for mobile devices such as phones.

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  Java Mail
  
  Javamail is a Java API which is used to send and receive email through SMTP,.POP3 and IMAP .

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  Java XML
  
  The Extensible Markup Language is the set of rules which is provide the help in encoding the document text into machine understandable form.

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  JUnit
  
  JUnit is a special framework of implementing testing in Java. It is providing for simple way to  explicitly test for specific test for specific area in java program.

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  Java Ant
  
  Ant is an open source code .It is Java-based build tool sponsored by Apache Software Foundation.

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  Java and Excel Sheets(POI APIs)
  
  The Apache POI API used to create and maintain various file formats of MS Office like Ms Excel Files, Ms Words, and Power POInt files using java.

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  Design Patterns
  
  Design pattern is a proven design solution to a common problem faced by software developers. Design Patterns are about design and interaction of objects.

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  CVS
  
  CVS is stand for Concurrent Version System.
  CVS is useful when more than one person work  on a particular file.

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  iText APIs(Java and PDF)
  
  iText is a library of classes which helps developers to improve the capabilities of their web server applications java
  

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  Networking
  
  networking is the practice of linking two or more computing devices together for the purpose of sharing data.

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  Java and Excel Sheets(Jexcel APIs)
  
  JExcel API refers as Java Excel API .JExcel is an open source java API by sourceforge. JExcel(Java Excel API) is used to read, write, and modify excel spreadsheets.

Packages

java.io

java.net

java.util

java.lang

JAVA APIS

iText

Javamail

Jexcel

POI