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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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/***reading Clob data from oracle table and setting to Pojo**/
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import oracle.sql.CLOB;


public class MessageDao {
private static String url = "jdbc:oracle:thin:@";
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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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Multi Threading , Producer consumer problem in Java

Multi threading is topic which is always fascinating for java developer. I feel its more about practical the theory. So here i wanted to present sample examples which clear understanding for several multi threading concept.

In Theory basically thread which is light weight process.Thread shares mostly same memory space.
I said mostly because there is some space called thread local which is not common to threads & separate for each thread. We create thread whenever we wanted to use multicore of processor although that doesn't mean single core cant use it. In single core context switching works among different running thread.

for example suppose there is website which is showing latest price as well as offer as well as doing order booking all these things can be assigned to different thread to provide parallel processing.

There are 2 ways for creating a thread.

Extend a thread & Implement a Runnable class. Extending a class is little avoided since it closed possibility for e…