Byte Wrapper Class

Posted by: Instanceofjava Posted date: June 17, 2015 / comment : 0

Byte Wrapper class Programs:


  • The java.lang.Byte class is used represent byte primitive value in form of Byte Object

  1. public final class Byte
  2. extends Number implements Comparable<Byte>

Byte Class Constructors:


1.Byte(byte value)
2.Byte(String s)

Byte Class Methods:

  • public byte byteValue() returns the value of this Byte as a byte.

Program:

  1. package com.instanceofjavatutorial;

  3. import java.lang.*; 

  5. public class ByteClass {

  7. public static void main(String[] args) {

  9.       Byte a;
  10.       a = new Byte("100");

  12.       byte t;
  13.       t = a.byteValue();

  15.       String s= "byte value of Byte object " + a + " is " + t;

  17.       System.out.println( s);

  19.    }
  20. }


Output:
  1. byte value of Byte object 100 is 100












Oracle and the Community Celebrate 20 Years of Java

Posted by: Instanceofjava Posted date: June 13, 2015 / comment : 0

Java 20 years


Oracle and the Community Celebrate 20 Years of Java 
  • Look Ahead to How Java Will Continue to Transform the Way We Work and Live Oracle, users and the development community worldwide are celebrating 20 years of Java this year. Today, Java serves as the critical backbone of software that touches both our work and personal lives. From innovations in enterprise big data, cloud, social, mobile and the Internet of Things, to connected cars, smartphones and video games, Java continues to help developers push the boundaries in technology innovation.

java 20 years



Evolution of the World’s #1 Programming Language
 
  • Introduced in 1995, Java is the programming language of choice for 9 million developers and today powers 7 billion devices. Improving road and air safety, collecting information from the world’s oceans for science applications, increasing grain crop quality and quantifying to help feed the hungry, simulating the human brain and musculoskeletal system, and gaming are some of the intriguing projects worldwide that use the Java technology. 
  • Enterprise developers can choose from an ecosystem of 30 Java EE 6 and Java EE 7 compatible implementations from 12 vendors. Additionally, more than 125 million Java-based media devices have been deployed and over 10 billion Java Cards have been shipped since Java’s introduction.
  • Under the stewardship of Oracle, two major platform releases including Java 7 and Java 8 have been delivered, with Java 9 slated for 2016. The Java Community Process (JCP) is more open and transparent than ever before, and serves as an integral element of community participation in the ongoing evolution of the technology. The OpenJDK Community, the place to collaborate on an open-source implementation of the Java Platform, Standard Edition, is continuously attracting new contributors to its already broad base of participation.
  • In March 2014, Oracle announced availability of Java SE 8 after receiving final approval in the Java Community process. This release, which included the largest upgrade to the Java programming model since the platform was introduced in 1995, was developed collaboratively in the OpenJDK Community. Soon after, in April 2014, the Java Platform, Micro Edition 8 (Java ME 8) and the related releases of Oracle's Java Embedded products were also made available after final approval in the Java Community Process.  With a consistent Java 8 platform across embedded devices, desktops, data centers and the cloud, customers can deploy applications faster; process and analyze in-flight data; and act on events as quickly as they occur.


java on cloud IOT

Ushering in the Next Era of Java 
  • Oracle and the Java community are now focused on delivering new innovations in Java 9. The key planned feature of this release is Project Jigsaw, which aims to modularize the platform in order to make it scalable to a wider range of devices, make it easier for developers to construct and maintain libraries and large applications, and improve security, maintainability, and performance. Other features slated for Java 9 include the Java Shell, an interactive tool for evaluating snippets of Java code; a new HTTP client API to support HTTP/2 and Web Sockets; a port to the ARM AArch64 architecture on Linux; and a variety of updates to existing APIs along with some significant performance improvements.
  • Visit the Duke’s Choice Award winners to see the remarkable work being done today by the Java community. 

“Java has grown and evolved to become one of the most important and dependable technologies in our industry today. Those who have chosen Java have been rewarded many times over with increases in performance, scalability, reliability, compatibility, and functionality.The Java ecosystem offers outstanding libraries, frameworks, and resources to help programmers from novice to expert alike.  The development of Java itself occurs in the transparent OpenJDK community.  With the considerable investment from Oracle and others in the community, we look forward to the next 20 years of Java’s evolution and growth.”

- Georges Saab, vice president of development, Java Platform Group, Oracle


 "IBM is celebrating Java's 20th anniversary as one of the most important industry led programming platforms spanning mobile, client and enterprise software platforms. IBM began its commitment to Java at its inception over two decades ago, and has seen the Java ecosystem and developer community bring unsurpassed value to the investments our clients have made in their Java based solutions. IBM looks forward to the next 20 years of growth and innovation in the Java ecosystem including Mobile, Cloud, Analytics and Internet of Things."  

-Harish Grama, vice president, Middleware Products, IBM Systems


“Programming languages don’t always live a long life, and those that do, don’t always enjoy a healthy one. But Java has stood the test of time and the test of the vast range of applications using it, from large enterprise systems to small device games.”
- Al Hilwa, IDC program director for Application Development Research





For Every 2 years Release will be there for java Under Oracle

  • The next version of java is Java 9 is going to be released on 2016 itself.  This shows how the team is working to ensure that there is everything for us to develop. 
  • Oracle and the java community now focusing on key project of Java 9 Project Jigsaw which helps us to build and maintain libraries and large applications and improves security maintainability and performance.

Get the education you need at better price

  • Oracle Training and Certification is offering 20 percent discount on all Java certification exams. The offer available globally is now open and expires on December 31, 2015.  at the time of registration you need to provide promotional code  as Java20
  • Clicke here for more details

Bloggers Meet At Oracle Hyderabad:

  • Today we attended an event organized by oracle on the occasion of "20 years of java".
  • One week back we got a message on instanceofjava Facebook page from oracle person 
    Gopal Kommuri saying that "I am writing on behalf of Oracle and trying to reach out to you to discuss about a bloggers meet we are planning to do in the next week".
  • I was surprised  because we www.instanceofjava.com are so young compared to others  but we are doing good on java and helping people like you and growing fast.
  • Anyway we are happy and said for sure will be attending the event.
  • Today june 13th 2015 morning 11 o clock we reached oracle office expecting that it was a big corporate event with lot of people.
  • Got a warm welcome from  Anita George and we entered into the meeting hall.
  • There are few Bloggers and higher officials.
  • Ms. Vandana Shenoy, Directory Corporate Communications, Oracle gave a warm welcome speech and introduced the presenters.
  • Sanket Atal, Group Vice President, India R&D, Oracle and he gave presentation titled “Java – 20 years of Innovation”. It was a very nice speech starting from how Java was created to the present day and how the future is promising for that how the oracle is doing things better to keep java alive.
  • Prior to Oracle Sanket held senior positions at MakeMy Trip and CA Technologies as CTO & Head of  Technology Center. He earlier worked with oracle in 1997 for over 13 years . He was the founding member of the team that setup the R&D centre for Oracle in the City of Portland Oregon , US.



                    • Inspiring and encouraging speech by Harshad Oak Founder , IndicThreads&Rightrix Solution , First Java Champion in India , Oracle ACE Director.
                    • Harshad has written many books on java including Oracle Jdeveloper 1og, Empowering J2EE Development, Pro Jakartha commons and J2EE 1.4 Bible.



                    • Innovative presentation by  Debraj Dutta  winner of the Oracle IoT Developer Challenge
                    • He showed us "Bot-So" which is taking photos and videos and calculating temperature by responding to twitter tweets designed using java 8 ,twitter 4j and Google drive  built on RaspberryPi hardware and Java platform.
                    • Bot-So is a smart social robot that interacts with you via twitter. The robot can be developed for remote home surveillance by sending commands via twitter. A tweet sent to the robot will trigger it to survey a space when the motion detector is triggered.
                    • He tweeted commands like "take a picture "  and it took a picture of us. it was amazing
                    • Java - Internet of everything.

                    • Here its Bot-So. (Robot-social)
                    • It can take a picture and video by rotating 120 degrees


                    • And we celebrated 20th java birth day by cutting a nice cake.

                    Happy birth day java
                    • After that had a group photo and nice lunch with team. Had a nice discussion with Sreekanth Narayanan.
                    •  met other bloggers and enjoyed the session and found it informative and encouraging.
                    • Its me Saidesh 1st from left and Indira second from right
                    Java 20 years




                    java 20 years




                    Boolean wrapper class example programs

                    Posted by: Instanceofjava Posted date: June 10, 2015 / comment : 0

                    • java.lang.Boolean Class is used to represent primitive boolean value in the form of object.

                    1.  public final class Boolean
                    2.    extends Object
                    3.       implements Serializable, Comparable<Boolean>
                       

                    Boolean Class Constructors:

                    1. public Boolean(boolean value)

                    1. Boolean obj=new Boolean(true);

                    Java code to convert boolean primitive to Boolean object
                    1. package com.instanceofjavatutorial;
                    2.  
                    3. public class BooleanDemo {
                    4.  
                    5. public static void main(String[] args) {
                    6.  


                    9.  Boolean obj=new Boolean(false);
                    10.  
                    11.  System.out.println(obj);
                    12.  
                    13.  
                    14. }
                    15. }

                    Output:
                    1. true

                    2. public Boolean(String s)

                    1. Boolean b=new Boolean("true");

                    Java Program to Convert String Object to Boolean Object

                    1. package com.instanceofjavatutorial;
                    2.  
                    3. public class BooleanDemo {
                    4.  
                    5. public static void main(String[] args) {
                    6.  
                    7.  String str="true";

                    9.  Boolean obj=new Boolean(str);
                    10.  
                    11.  System.out.println(obj);
                    12.  
                    13.  
                    14. }
                    15. }

                    Output:
                    1. true

                    Boolean class Methods:

                    1.public boolean booleanValue()

                    • This method gives the boolean primitive value from Boolean object
                    • See below java code which explains how to get boolean primitive value and assig to primitive variable from Boolean Object.

                    Java Program To Convert boolean primitive value to Boolean Object and To get boolean value from Boolean Object

                    1. package com.instanceofjavatutorial;
                    2.  
                    3. public class BooleanDemo {
                    4.  
                    5. public static void main(String[] args) {
                    6.  
                    7. // converting boolean variable in to Boolean Object
                    8.  Boolean bobj=new Boolean(true);
                    9.  
                    10.  System.out.println(bobj);
                    11.  
                    12. //converting Bolean object into boolean primitive value
                    13.  boolean bval=bobj.booleanValue();
                    14.  
                    15.  System.out.println(bval);
                    16.  
                    17. }
                    18. }

                    Output:
                    1. true
                    2. true

                    Google IO 2015 Main Features

                    Posted by: Instanceofjava Posted date: May 28, 2015 / comment : 0

                    • Google announced a new smart home platform called Brillo on stage at its annual Google I/O developers 
                    • At Google I/O 2015 Google officially announced Project Brillo, a new platform for the Internet of Things.
                    watch live HereGoogle IO 2015

                    Whats NEW????.... It's a LOT !!!!

                    • Google announced a new smart home platform called Brillo on stage at its annual Google I/O developers 
                    • At Google I/O 2015 Google officially announced Project Brillo, a new platform for the Internet of Things.
                    • This is one of the biggest announcements from today's developer conference. Unlimited photo and video
                    • Google Maps, including turn-by-turn voice directions, to be available offline.. 
                    • Android M is big brother for sure. Google's latest version of Android will remind you to pick up your dry 
                    • Have you tried this fun Google trick yet? #YouNeedToTryThis #BarrelRoll #Google #Funfact  
                    • Google Cardboard received a big update today and it's also compatible with iOS now.
                    • Google is adding a family friendly section to Google Play! 
                    • Google I/O 2015 Keynote slides look pretty sleek and consistent - good to see! 
                    • Google reveals their second virtual reality headset for phones, a larger Google Cardboard. Clay Bavor of Google 

                    public static void main(String[] args) in Java

                    Posted by: Instanceofjava Posted date: May 23, 2015 / comment : 4 ,

                    • main method is a standard method used by JVM to execute any java program(Java SE).
                    • Lets see an example class without main method.

                    1. package instanceofjava;
                    2. public Demo{
                    3.  
                    4. }


                    • This class will compile fine but while executing JVM fails to find the main method in that class
                    • So it will throw an exception: NoSuchMethodError:main

                    1. package instanceofjava;
                    2. public Demo{
                    3. public static void main(String [] args){
                    4.  
                    5. }
                    6. } 
                    • This program will compile and executed. Because at run time JVM calls the main method on that class.

                    Why main method is public?

                    •  To call by JVM from anywhere main method should be public.
                    • If JVM wants to call our method outside of our package then our class method should be public.

                    1. package instanceofjava;
                    2. public MainDemo{
                    3. public static void main(String [] args){
                    4.  
                    5. }
                    6. }

                    public static void main(string args) interview Questions

                    Why main method is static?

                    • To execute main method without creating object then the main method oshould be static so that JVM will call main method by using class name itself.

                    Why main method return type is void?

                    • main method wont return anything to JVM so its return type is void.

                     Why the name main?

                    • This is the name which is configured in the JVM.

                    Why the arguments String[] args?

                    •  Command line arguments.
                    • String array variable name args : by the naming conventions they named like that we can write any valid variable name.

                    Can we write static public void main(String [] args)?

                    • Yes we can define main method like static public void main(String[] args){}
                    •  Order of modifiers we can change.

                    1. package instanceofjava;
                    2. public MainDemo{
                    3. static public void main(String [] args){
                    4.  
                    5. }
                    6. }

                    What are the possible public static void main(String [] args)method declaration with String[] args?

                    • public static void main(String[] args){ }
                    • public static void main(String []args){ }
                    • public static void main(String args[] ){ }
                    • public static void main(String... args){ } 
                    • Instead of args can place valid java identifier.

                    Can we declared main method with final modifier?

                    • Yes we can define main method with final modifier.

                    1. package instanceofjava;
                    2. public MainDemo{
                    3. public static final void main(String [] args){
                    4.  
                    5. }
                    6. } 

                    Main method with all possible modifiers:

                     

                    1. package instanceofjava;
                    2. public MainDemo{
                    3. static final synchronized public void main(String [] args){
                    4.  
                    5.  System.out.println("Main method");
                    6.  
                    7. }
                    8. } 

                    Output:

                    1. Main method

                    Overloading main method:

                    • We can declare multiple main methods with same name as per overloading concept.  
                    • So we can overload main method but every time JVM looks for main method with String[] args method.
                    • Lets see an example program on main method overloading.
                    • main(String[] args) method will be called automatically by JVM.
                    • If we want to call other methods we need to call explicitly.

                     

                    1. package instanceofjava;
                    2. public MainDemo{
                    3. public static void main(String [] args){
                    4.  
                    5.  System.out.println("Main method String [] args");
                    6.  
                    7. } 
                    8. public static void main(int[] args){
                    9.  
                    10.  System.out.println("Main method int[] args");
                    11.  
                    12. }
                    13.  
                    14. } 





                    Output:

                    1. Main method String [] args


                    Main method Inheritance:

                    • Inheritance concept is applicable for main method.
                    • If a sub class not having main method and extending a super class which is having main method.
                    • Then if we execute super class main method will be executed fine.
                    • If we execute sub class which is not having main method also executed fine and super class main method will be called.

                    1. package instanceofjava;
                    2. public A{
                    3. public static void main(String [] args){
                    4.  
                    5.  System.out.println("Main method of class A");
                    6.  
                    7. } 
                    8.  
                    9. } 



                    Output:

                    1. Main method of class A

                     

                    1. package instanceofjava;
                    2. public B extends A{
                    3.  
                    4. } 
                    Output:

                    1. Main method of class A

                    What happen if both super and sub class having main method?

                    • Actually its not overriding concept here. it is a method hiding concept in this scenario regarding with main method.

                    1. package instanceofjava;
                    2. public A{
                    3. public static void main(String [] args){
                    4.  
                    5.  System.out.println("Main method of class A");
                    6.  
                    7. } 
                    8.  
                    9. } 

                    Output:

                    1. Main method of class A


                    1. package instanceofjava;
                    2. public B extends A{
                    3. public static void main(String [] args){
                    4.  
                    5.  System.out.println("Main method of class B");
                    6.  
                    7. } 
                    8.  
                    9. } 


                    Output:

                    1. Main method of class B

                    Static block in Java

                    Posted by: Instanceofjava Posted date: May 23, 2015 / comment : 0 ,

                    • Static variables are class level variables and without instantiating class we can access these variables.

                      1. Static int a;


                    • Class loading time itself these variables gets memory
                    • Static methods are the methods with static keyword are class level. without creating the object of the class we can call these static methods.

                      1. public static void show(){ 
                      2.  
                      3. }

                    • Now its time to discuss about static blocks.
                    • Static block also known as static initializer
                    • Static blocks are the blocks with static keyword.
                    • Static blocks wont have any name in its prototype.
                    • Static blocks are class level.
                    • Static block will be executed only once.
                    • No return statements.
                    • No arguments.
                    • No this or super keywords supported.
                      •  
                      1. static{ 
                      2.  
                      3.  }

                       

                    What is the need of static block?

                    • Static blocks will be executed at the time of class loading.
                    • So if you want any logic that needs to be executed at the time of class loading that logic need to place inside the static block so that it will be executed at the time of class loading. 
                    • To initialize the static variables while class loading itself we need static block.
                    • If we have multiple classes then if you want to see the order of those classes loading then static block needed.

                    When to use static blocks?

                    • If you want to access static variables before executing the constructor.
                    • If you want to execute your code only once even any number of objects created.
                    • If you want to initialize static constants.

                    When and where static blocks will be executed?

                    • Static blocks will be executed at the time of class loading by the JVM  by creating separate stack frames in java stacks area (Please refer JVM Architecture  to know about stacks area).
                    • Static blocks will be executed in the order they defined from top to bottom.



                    1. package com.instanceofjava;
                    2.  
                    3. class StaticBlockDemo 
                    4. {
                    5.  
                    6. static{
                    7.       System.out.println("First static block executed");
                    8. }
                    9.  
                    10. static{
                    11.      System.out.println("Second static block executed");
                    12. }
                    13.  
                    14. static{
                    15.      System.out.println("Third static block executed");
                    16. }
                    17.  
                    18. }
                       
                    Output:
                    1. First static block executed
                    2. Second static block executed
                    3. Third static block executed

                    Order of execution of static block and main method:

                    1. package com.instanceofjava;
                    2.  
                    3. class StaticBlockDemo 
                    4. {
                    5.  
                    6. public static void main (String[] args) throws java.lang.Exception
                    7. {
                    8.         System.out.println("Main method executed");
                    9. }
                    10.  
                    11. static{
                    12.       System.out.println("First static block executed");
                    13. }
                    14.  
                    15. static{
                    16.      System.out.println("Second static block executed");
                    17. }
                    18.  
                    19. static{
                    20.      System.out.println("Third static block executed");
                    21. }
                    22.  
                    23. }
                       
                    Output:
                    1. First static block executed
                    2. Second static block executed
                    3. Third static block executed
                    4. Main method executed


                    Order of execution of Static block and constructor:

                     

                    1. package com.instanceofjava;
                    2.  
                    3. class StaticBlockDemo 
                    4. {
                    5.  
                    6. StaticBlockDemo(){
                    7.  
                    8.   System.out.println("Constructor executed");
                    9.  
                    10. }
                    11. public static void main (String[] args) throws java.lang.Exception
                    12. {
                    13.  
                    14.     System.out.println("Main method executed");
                    15.     StaticBlockDemo obj = new StaticBlockDemo();
                    16.  
                    17. }
                    18.  
                    19. static{
                    20.       System.out.println("First static block executed");
                    21. }
                    22.  
                    23. static{
                    24.      System.out.println("Second static block executed");
                    25. }
                    26.  
                    27. static{
                    28.      System.out.println("Third static block executed");
                    29. }
                    30.  
                    31. }
                       


                    Output:
                    1. First static block executed
                    2. Second static block executed
                    3. Third static block executed
                    4. Main method executed
                    5. Constructor executed

                    What is the output of following program:


                    1. package com.instanceofjava;
                    2.  
                    3. class StaticBlockDemo 
                    4. {
                    5.  
                    6.   static int a=getNum();

                    8. public static int getNum(){
                    9.  
                    10. System.out.println("In method m1()");
                    11. return 10;
                    12.  
                    13. }

                    15. public static void main (String[] args) throws java.lang.Exception
                    16. {
                    17.  
                    18.     System.out.println("Main method executed");
                    19.   
                    20.  
                    21. }
                    22.  
                    23. static{
                    24.       System.out.println("First static block executed");
                    25. }
                    26.  
                    27. static{
                    28.      System.out.println("Second static block executed");
                    29. }
                    30.  
                    31. static{
                    32.      System.out.println("Third static block executed");
                    33. }
                    34.  
                    35. }
                       
                    Output:
                    1. In method m1()
                    2. First static block executed
                    3. Second static block executed
                    4. Third static block executed
                    5. Main method executed


                    Java Jsp Interview Questions

                    Posted by: Instanceofjava Posted date: May 19, 2015 / comment : 0 , ,

                    1.Explain JSP life Cycle methods?

                    • jsp engine controls the life cycle of jsp
                    • Jsp life cycle is described by three life cycle methods and six life cycle phases


                    Jsp life cycle methods :

                    • jspInit()
                    • _jspService()
                    • jspDestroy()


                    • Jspinit() method is invoked when JSP page is initialized.
                    • The _jspService() method corresponds to the body of the jsp page.
                    • This method is defined automatically by the JSp container and should never be defined y the JSP page author.

                    Jsp Life cycle Phases: 

                    • Translation phase
                    • Compilation phase
                    • Instantiation phase
                    • initialization phase
                    • Servicing phase
                    • Destruction phase

                    Read More at : JSP Life Cycle

                    2. What are the Jsp Implicit Objects?


                    • Implicit objects in jsp are the objects that are created by the container automatically and the container makes all these 9 implicit objects to the developer.
                    • We do not need to create them explicitly, since these objects are created and automatically by container and are accessed using standard variables(objects) are called implicit objects.
                    • The following are of implicit variables available in the JSP.  


                    1. out
                    2. request
                    3. response
                    4. config
                    5. application
                    6. session
                    7. pagecontext
                    8. page
                    9. exception
                    Read More at: 9 Jsp Impicit Objects in java

                    3. Explain Jsp Scripting Elements?

                    • Jsp scripting elements are used to embed jva code in to the jsp.
                    • Jsp scripting elements are three types
                      1. Declaration
                      2. Expression
                      3. Scriplet
                    Read More at: Jsp Scripting Elements



                    4. What are the Directives in Jsp?

                    • A jsp directive is a translation time instruction to the jsp engine.
                    • we have three kinds of directives.
                    1. Page directive
                    2. Include directive
                    3. Taglib directive

                     Read More at: Jsp Directive Elements


                     5. What are the differences between include directive and include action?


                    Java Jsp interview Questions

                     

                    6. How to disable session in JSP?

                    • By using page directive
                    • <%@ page session="false" %> 

                    7. How can we handle exceptions in a JSP page?

                    • We can handle exception in jsp by using error page element of page directive 

                    • The errorPage attribute tells the JSP engine which page to display if there is an error while the current page runs.
                      The value of the errorPage attribute is a relative URL.
                      The following directive displays MyErrorPage.jsp when all uncaught exceptions are thrown

                      Syntax:

                      errorPage="url"

                      Example:

                      <%@ page errorPage="error.jsp"%>

                    8.How can we override jspInit() and jspDestroy() methods in a jsp?

                    • Both methods are executed once in a life cycle of a jsp.
                    • We can override these two method as shown below.
                    • <%!
                          public void jspInit() {
                              . . .
                          }
                      %>
                    • <%!    
                          public void jspDestroy() {
                              . . .   
                          }
                      %>

                    9.Can a JSP extend a java class?

                    • Yes we can extend a java class in jsp
                    • <%@ include page extends="classname" %>
                    • We can do this because jsp will convert to a servlet so a servlet can extend a class its fine

                    10.How can we pass information from one jsp to included jsp page?

                    • <jsp:include page="employeedetail.jsp" flush="true">
                    • <jsp:param name="name" value="abc"/>
                    • <jsp:param name="id" value="220"/>

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