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 In Java we have some thing called JVM, Java virtual machine which is responsible for all the processing / running of java code. Byte code runs on this JVM which is basically run time environment. JVM is responsible for loading, validating, executing code.You need to run java code means you need jvm.

So What is JRE??

JRE is basically physical implementation of JVM which includes JVM & other libraries need to run code. JRE is just one implementation provided by sun. Many other implementation also exist released by other companies as well.


JDK is basically java development kit which actually required to develop java applications.
Its pack is having element like JRE, libraries & other java development tools required.
tools for compiling, running, performance management etc.

So finally about Java .
Team of Engineer called Greem Team consist of members named James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. originally it was developed for embedded system & it named as Greentalk which then rename to oak ( was registered with oak technologies) then changed to Java as it was was island of Indonesia & producer of coffee.

Some Key versions of Java

  • Major releases based on classes/packages introduced are:
  1. JDK Version 1.0
  2. J2SE Version 1.4
  3. J2SE Version 5.0
  4. Java SE 6
  5. Java SE 8
  • Major releases based on new concepts introduced are:
  1. JDK Version 1.1 (RMI)
  2. J2SE Version 1.2 (Collection Classes)
  3. J2SE Version 5.0 (Enums, Generics)
  4. Java SE 8 (Lambda Expressions, Method Reference, Streams)


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import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import oracle.sql.CLOB;


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Portable Java 8/ JDK8 setup without admin rights

Some time we got machine to work where we don't have access rights to install anything or if you do not want to install. You can get latest jdk running by this trick. Just follow step step & do comment if you like it.

Step by Step details to get running java from .exe setup without any admin rights. Get portable 7 zip from portableapps.comdownload java 8 from oracle 7 zip & extract jdk-8u102-windows-x64.exeyou will see below folders                .data                .pdata                .rdata                .reloc                .rsrc                .text                CERTIFICATE

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         6.extract it it some folder where you can find again extract that to some folder say Java & copy it to very first folder of setup along with .data,.rsrc etc.
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GOF Design pattern with Java & Real World Examples

What are design patterns? 

So basically these are just collection of best practices to solve recurring problem by different kind of class arrangement. These arrangement could be based on creation of object or structural basis or on basis of required behavior.

Creational Design Pattern
Prototype Designpattern we will like to use this designpattern whenever creation of initial object & setting required default values is costly. So we just create 1 object & later on whenever more objects required we can provide initial object by just cloning of given object.Java Example is java.lang.Object#clone()
Builder DesignPattern When we jave object structure are complex and complicated we would go for this. we will be separating object creation from internal representation. With help of some simple interface we would create complicated Object.
Singleton When we need one instance per JVM. Example : Java Run time environment Java.lang.System.  java.lang.StringBuilder, Spring Beans are singleton …