tag:blogger.com,1999:blog-793753016956489323Sat, 18 Jul 2026 05:08:41 +0000javamultitaskingmultithreading in javaDIInversion of controljdbcgitheapincrease heap sizeinterview questionsjava heap spacemongodb installationspring frameworkthreadstypes of multitasking in javaDDLDMLDependency InjectionFactory patternOutOfMemoryErrorRESTSQL statementsServletTCLamendapache httpclientdatabasedelete tag in giteclipseequinoxexception interview questions.git taggziphttp componentsimmutabilityimmutable objectsinsert imageinstallationintegrateinter thread communicationjava web startjavawsjavaws.exejerseylinuxmavenmongomongo on windowsmongodmongodbmonitornotifyAllobject lockobject oriented programmingoopsoracleosgiout of memory erroroutofmemory errorperm genpost request using httpclientrebaserowsetrunnable interfacesonarsynchronizationsynchronized blockssynchronized methodsthread classthread creationubuntuunixuntarwaitweblogicA blog about java tutorials , java interview questions.http://javasolutionsonline.blogspot.com/noreply@blogger.com (Anonymous)Blogger38125tag:blogger.com,1999:blog-793753016956489323.post-61691052678227788Thu, 18 Sep 2014 07:34:00 +00002014-10-12T20:35:56.449+05:30gitrebase Have you faced a merge conflict while performing git rebase operation ? This is quite possible  if two commits modify the same line in the same file. Now git is confused which change to apply. Git gives us several options in such a case : git rebase --continue git rebase --abort git rebase --skip 1. git rebase --continue Used in case if you have manually corrected the http://javasolutionsonline.blogspot.com/2014/09/Howtoresolvemergeconflictsaftergitrebase.htmlnoreply@blogger.com (Anonymous)1India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-4854888548684168248Mon, 01 Sep 2014 15:15:00 +00002014-09-01T20:45:11.631+05:30gziplinuxubuntuunixuntar Lets say that the name of file is - test.tar.gz From the terminal, change to the directory where tar file is located. Now to extract the file to the current directory , run the command   tar -zxvf test.tar.gz To extract the file to a specific directory , run tar -C /directory_name -zxvf test.tar.gz NOTE : The extensions .tgz and .tar.gz are equivalent and both signify that a tar http://javasolutionsonline.blogspot.com/2014/09/how-to-open-or-untar-targz-file-in.htmlnoreply@blogger.com (Anonymous)0India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-1172431389370629442Thu, 01 May 2014 09:42:00 +00002014-05-01T15:13:37.035+05:30amendgit Have you ever faced a situation where you left something out of your last commit ? It may be a file or an extra change to a file you just committed.  Such kind of scenarios can easily be handled with Git amend command . How does it work ? 1. Just add the file using git add ( Like what we do for         normal commit ).     git add <file> 2. Nowhttp://javasolutionsonline.blogspot.com/2014/05/how-to-amend-last-commit-in-git.htmlnoreply@blogger.com (Anonymous)0India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-3097362120516913541Tue, 29 Apr 2014 14:54:00 +00002014-04-29T20:24:57.093+05:30maven Problem Description : My Eclipse IDE gives errors whenever I try to build the project . The problems tab shows the message as given below Unbound classpath variable: 'M2_REPO/...' Solution : M2_REPO is a classpath variable that tells eclipse where maven repository is on your disk . Setting M2_REPO  Open Eclipse Preferences [Window -> Preferences] Go to [Java -> Buildhttp://javasolutionsonline.blogspot.com/2014/04/unbound-classpath-variable-m2repo-error.htmlnoreply@blogger.com (Anonymous)1India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-5374711601255135647Sun, 30 Mar 2014 12:14:00 +00002014-03-30T17:44:51.567+05:30jdbcrowset A RowSet ( javax.sql.RowSet ) is an object that encapsulates a set of rows from either Java Database Connectivity (JDBC) result sets or tabular data sources like a file or spreadsheet. RowSets support component-based development models like JavaBeans, with a standard set of properties and an event notification mechanism.Interfaces that extends RowSet are  : JdbcRowSethttp://javasolutionsonline.blogspot.com/2014/03/what-is-jdbc-rowset_30.htmlnoreply@blogger.com (Anonymous)0India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-344607136680530431Sat, 29 Mar 2014 17:01:00 +00002014-03-29T22:31:47.084+05:30equinoxosgi This post shows how to run Equinox as an OSGi stand-alone runtime. Download org.eclipse.osgi_.jar from here. The same jar exists in eclipse installation directory ( plugin folder ). Copy the jar and paste into a new directory. Example - C:\osgi\org.eclipse.osgi_3.9.1.v20140110-1610.jar Starting the OSGi server : java -jar org.eclipse.osgi_3.9.1.v20140110-1610.jar -consolehttp://javasolutionsonline.blogspot.com/2014/03/how-to-run-standalone-osgi-server.htmlnoreply@blogger.com (Anonymous)0India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-1802842205938309235Sat, 29 Mar 2014 12:29:00 +00002014-03-29T17:59:44.146+05:30jdbc The JDBC API uses a driver manager and database-specific drivers to provide transparent connectivity to heterogeneous databases. The JDBC driver manager ensures that the correct driver is used to access each data source.        The JDBC Architecture consists of two layers: The JDBC API , which provides the application-to-JDBC Driver Manager&http://javasolutionsonline.blogspot.com/2014/03/understanding-jdbc-architecture.htmlnoreply@blogger.com (Anonymous)0India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-4657577622890645899Thu, 27 Feb 2014 06:13:00 +00002014-02-27T11:47:11.422+05:30exception interview questions.interview questionsjava What is Exception in Java ? What happens when a method throws an exception ? Explain Java Exception Hierarchy? What are important methods of Java Exception Class? What is OutOfMemoryError in Java? What is the concept of multi-catch block ? What is difference between Checked and Unchecked Exception in Java? What is difference between throw and throws keyword in Java? What happens when http://javasolutionsonline.blogspot.com/2014/02/java-exception-interview-questions-and.htmlnoreply@blogger.com (Anonymous)1India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-265915208904410033Tue, 25 Feb 2014 12:46:00 +00002014-12-08T15:30:10.981+05:30interview questionsjavaServlet What is a Servlet ? What is the hierarchy of servlet api ? What are the uses of Servlet? What are the advantages of Servlet over CGI? Define servlet life cycle? Why do we need a constructor in a servlet if we use the init method ? How the servlet is loaded ? How a Servlet is unloaded ? What is the GenericServlet ? What is the difference between GenericServlet and HttpServlet ? Why is http://javasolutionsonline.blogspot.com/2014/02/servlet-interview-questions.htmlnoreply@blogger.com (Anonymous)4India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-1140618803122388044Mon, 24 Feb 2014 11:27:00 +00002014-02-24T18:40:09.298+05:30object oriented programmingoops What is an Object ? What is Class ? What are the principle concepts of OOPS? What is Inheritance? What is Polymorphism? What is Abstraction? What is Encapsulation? What is the difference between abstraction and encapsulation? Explain the different forms of Polymorphism. What is runtime polymorphism or dynamic method dispatch? What is Dynamic Binding? What is method overloading? What is methodhttp://javasolutionsonline.blogspot.com/2014/02/object-oriented-programming-concepts-OOP-interview-questions.htmlnoreply@blogger.com (Anonymous)14India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-829090219967676635Sun, 23 Feb 2014 18:03:00 +00002014-08-09T12:30:26.632+05:30 GENERAL COLLECTION QUESTIONS What is Java collection framework ? Why Collection does not extends Serializable or Cloneable ? Why Map interface does not extends Collection interface ? What is UnsupportedOperationException? What is read-only collection ? How can we create the same? What are thread safe collections ? What are concurrent collection classes? LIST INTERFACE What is List http://javasolutionsonline.blogspot.com/2014/02/collections-interview-questions-in-java.htmlnoreply@blogger.com (Anonymous)7India20.593684 78.962880000000041-8.580994 37.654286000000042 49.768361999999996 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-6396601944352628978Thu, 20 Feb 2014 17:20:00 +00002014-12-08T15:22:03.013+05:30multitaskingmultithreading in java Hi.  This post dedicated to some basic questions on Java multithreading concepts. Multithreading is a topic that is asked in all the interviews, and  especially in companies working on banking solutions . What is a Thread? What is thread priority ? How can we set the priority of a thread ? What is the difference between Thread and Process? What are the advantages and http://javasolutionsonline.blogspot.com/2014/02/20-basic-multithreading-interview.htmlnoreply@blogger.com (Anonymous)1India20.593684 78.962880000000041-8.5815185000000014 37.654286000000042 49.7688865 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-5313355026853958323Sun, 16 Feb 2014 11:36:00 +00002014-02-18T12:07:20.488+05:30jerseyREST What are RESTful Web Services? HTTP Methods Constraints Client–Server Layered System Stateless Communication Caching Constraint Code on Demand Uniform Interface When should we use REST ? When to use SOAP based design JAX-RS Important annotations in JAX-RS Implementations of JAX-RS Introducing Jersey Sample application in Jersey Step 1 - Creating maven project Step 2 - Adding http://javasolutionsonline.blogspot.com/2014/02/creating-simple-web-service-with-jersey.htmlnoreply@blogger.com (Anonymous)7India20.593684 78.962880000000041-8.5815185000000014 37.654286000000042 49.7688865 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-7488832483697503200Fri, 31 Jan 2014 12:20:00 +00002014-01-31T17:59:20.605+05:30sonar What is Code Analysis ? Benefits Introduction to Sonar Sonar Dashboard Features Unit tests inspection Quality Profiles Issues Drilldown Application Lifecycle Management Time Machine Well we all know that code analysis is a very basic and important part of software development process .  It doesn't matter how much experience we have in software development , we usually end up inhttp://javasolutionsonline.blogspot.com/2014/01/sonar-effective-code-reviewer.htmlnoreply@blogger.com (Anonymous)0India20.593684 78.962880000000041-8.5815185000000014 37.654286000000042 49.7688865 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-8158342237885400779Sun, 12 Jan 2014 15:24:00 +00002014-01-13T23:32:43.073+05:30DIFactory patternInversion of controlspring framework Dependency Injection ( DI ) and Factory pattern might look related to each other but there is a difference between them . Factory take the responsibility of creating an object while DI inverse the process of how an object obtains the dependencies . DI gives the responsibility of injecting dependencies to an external entity. Example :  1. While using a factory , http://javasolutionsonline.blogspot.com/2014/01/dependency-injection-vs-factory-pattern.htmlnoreply@blogger.com (Anonymous)0India20.593684 78.962880000000041-8.5815185000000014 37.654286000000042 49.7688865 120.27147400000004tag:blogger.com,1999:blog-793753016956489323.post-5688606965422336851Sat, 11 Jan 2014 21:12:00 +00002014-01-12T21:40:56.637+05:30DIInversion of controlspring framework What is Dependency Injection ( DI ) ? Types of DI. Advantages. DI with Spring framework. Constructor based DI or Setter based DI What is Dependency Injection ( DI ) ? Dependency Injection means inversion of responsibilities with regard to how an object obtains references to collaborating objects. When applying DI , objects are given their dependencieshttp://javasolutionsonline.blogspot.com/2014/01/dependency-injection-with-spring.htmlnoreply@blogger.com (Anonymous)0India28.608637026615575 77.228393554687528.385636026615575 76.9056700546875 28.831638026615575 77.5511170546875tag:blogger.com,1999:blog-793753016956489323.post-8414084344983224175Mon, 04 Nov 2013 16:45:00 +00002013-11-05T10:33:12.006+05:30javajava web startjavawsjavaws.exe Java Web Start is an application deployment technology that can be used to download and run java applications from the web . The download and installation can be done with a single step without going through the complicated installation process. Java Web Start also caches the downloaded application on local machine so the subsequent invocations are instantaneous as all the required http://javasolutionsonline.blogspot.com/2013/11/what-is-java-web-start-javawsexe.htmlnoreply@blogger.com (Anonymous)0Gurgaon, Haryana, India28.4594965 77.02663830000005928.236067 76.703914800000064 28.682926000000002 77.349361800000054tag:blogger.com,1999:blog-793753016956489323.post-1685581931557479537Mon, 07 Oct 2013 14:01:00 +00002013-10-08T11:49:53.108+05:30inter thread communicationnotifyAllwait Lets start with the methods that facilitates Inter Thread Communication in Java . All these methods are present in java.lang.Object class . wait() wait() method is used to instruct the current thread to release the object's lock and get suspended until some other thread invokes notify() or notifyAll() method for the same monitor. notify() notify() method is used to wake up a thread that http://javasolutionsonline.blogspot.com/2013/10/inter-thread-communication-showing.htmlnoreply@blogger.com (Anonymous)0tag:blogger.com,1999:blog-793753016956489323.post-9124157656978223306Fri, 04 Oct 2013 19:47:00 +00002013-10-12T21:53:02.368+05:30apache httpclienthttp componentspost request using httpclient Hi . In my previous posts , we talked about the basics of HttpClient ( Click here ) and how to use it safely in a multithreaded environment ( Click here )  . In this post we will learn how we can send POST request to a server using HttpClient .  Get Ready : Download HttpClient dependencies and put them in the classpath of your application or if you are a http://javasolutionsonline.blogspot.com/2013/10/sending-post-request-using-http.htmlnoreply@blogger.com (Anonymous)5tag:blogger.com,1999:blog-793753016956489323.post-7896633259756139145Sat, 21 Sep 2013 18:01:00 +00002013-10-06T14:42:54.971+05:30monitormultitaskingmultithreading in javaobject locksynchronizationsynchronized blockssynchronized methods What is Synchronization ? Synchronization is a way to control the access to a shared resource in multithreaded environment in such a way that only one thread can access a shared resource at a time. Synchronization is achieved through the concept of monitor. A monitor is an exclusive lock that is obtained on an object by a thread when a synchronized method is called on the object ( or a http://javasolutionsonline.blogspot.com/2013/09/intrinsic-locks-and-synchronization.htmlnoreply@blogger.com (Anonymous)0tag:blogger.com,1999:blog-793753016956489323.post-5586420560751169669Fri, 20 Sep 2013 19:10:00 +00002013-09-21T00:40:25.595+05:30 The situation where multiple threads try to operate on a shared resource without proper synchronization  and sequence of their operations interleave is  Race Condition ( Also see Thread interference and Memory consistency errors) . Example 1 . The most basic example to describe a Race condition is a Counter class  that increments value of an instance variable .  class http://javasolutionsonline.blogspot.com/2013/09/race-condition-in-concurrency.htmlnoreply@blogger.com (Anonymous)2tag:blogger.com,1999:blog-793753016956489323.post-7340691796209312749Sat, 14 Sep 2013 14:47:00 +00002013-10-05T14:27:46.893+05:30 Hi Guys !!! So this blog is all about the Object Oriented Programming  concepts . Lets start from the very basic concept of Object and Class . What is an Object ? Well It is the most basic concept and a key to understand the Object-Oriented programming . Object is an entity that has two characteristics ,  State and Behavior . Some examples of real world object can be : Bike , http://javasolutionsonline.blogspot.com/2013/09/oop-concept-in-java.htmlnoreply@blogger.com (Anonymous)17tag:blogger.com,1999:blog-793753016956489323.post-4385161675649336996Wed, 11 Sep 2013 06:09:00 +00002013-09-13T22:46:36.097+05:30 In my previous post ( Understanding commons HttpClient with example.) , we discussed about the basics of HttpClient with an example . In this post we will learn how we can use HttpClient in a multi-threaded environment. Why use HttpClient in Multi-threaded environment ? Now that's a good question . Suppose we need to download multiple files simultaneously .For example  in my http://javasolutionsonline.blogspot.com/2013/09/using-httpclient-safely-in-multi.htmlnoreply@blogger.com (Anonymous)0tag:blogger.com,1999:blog-793753016956489323.post-6829311828668001725Mon, 09 Sep 2013 05:31:00 +00002013-09-09T18:56:56.703+05:30 What is HttpClient : HttpClient is a client side  HTTP transport library whose purpose is to transmit and receive HTTP messages. The HTTP (Hyper Text Transfer Protocol ) is the most significant protocol used on the internet today. HttpClient can be used by anyone building HTTP-aware client applications such as Web Browsers , Web services clients or any system that uses HTTP protocol http://javasolutionsonline.blogspot.com/2013/09/understanding-commons-httpclient-with.htmlnoreply@blogger.com (Anonymous)0tag:blogger.com,1999:blog-793753016956489323.post-3052136707622291141Tue, 03 Sep 2013 17:46:00 +00002013-09-14T21:30:59.618+05:30 Generally threads communicates by sharing member variables and the Object references members refer to. Well this type of communication is extremely efficient but can cause two kind of problems : 1. Thread Interference  2. Memory Consistency Errors  Interference occurs when two operations , running in different threads , but acting on the same data , interleave. See the Counter http://javasolutionsonline.blogspot.com/2013/09/thread-interference-and-memory.htmlnoreply@blogger.com (Anonymous)0