The error message "searchBase must not be null (an empty string is acceptable)" is specific to LDAP (Lightweight Directory Access Protocol) and it usually occurs when trying to perform a sea… Read More

The error message you're seeing suggests that there was a problem with the SSL/TLS handshake between the Kafka client and the server. This could be caused by a number of issues, including:In… Read More

Java provides several libraries for SSL/TLS support, which can be used to secure communication between a client and server over the internet. Here are some of the popular Java SSL libraries:… Read More

Kafka is a distributed streaming platform that is designed to handle high volumes of data in real-time. Like any other distributed system, Kafka may encounter several issues that can affect… Read More

What is Java? Java is a high-level, object-oriented programming language developed by Sun Microsystems. It is platform-independent and can run on any operating system that has a Java Virtual… Read More

You can use the getActualMaximum method in Calendar to retrieve the maximum day of a month.import java.util.Calendar;import java.util.Scanner;public class EndDateOfMonth {  &nb… Read More

Fail-safe and fail-fast operations in Java are related to the behavior of iterators when a collection is modified while it is being iterated.A fail-safe iterator creates a copy of the collec… Read More

[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK? This error message typically appears when you try to compile Java code without having… Read More

It is always convenient to copy a selected set of data to a table directly from another table using nested select queries.INSERT INTO table1 (column1, column2, column3) SELECT column1, colum… Read More

Spring Transactions provide a way to manage transactions in Spring-based applications. Transactions help ensure data consistency and integrity by ensuring that a group of related database op… Read More

In Java, a String object is immutable, meaning that its value cannot be changed once it is created. This design decision was made for several reasons, including:Security: Because String obje… Read More

Kotlin is a statically-typed programming language that has been gaining popularity over the years due to its advantages over Java. Developed by JetBrains, the creators of IntelliJ IDEA, Kotl… Read More

Error MessageExpected EOF, found '*' at 8When trying to preview the dataset in edit mode.Cause of the issue@ prefix on the dynamic query section with generic SQL query@SELECT * FROM Books WH… Read More

Error MessagesThere was an error while overriding 'app_name_pipeline_varibale' parameter because of 'SyntaxError: Unexpected token M in JSON at position 50', make sure it follows JavaScript… Read More

While we are working with SQL Server, it is often required to see the tables under the different schemas. You can still do that via SQL Server Management Studio. But if you need to join… Read More

Error Message[error] Deployment template validation failed: 'Template parameter JToken type is not valid. Expected 'Integer'. Actual 'String'. Please see https://aka.ms/resource-manager-para… Read More

Azure Logic App Issue on Azure Storage Account ConnectivityContext Azure logic apps with Azure Storage account connectivityError Message{    "status": 400,    "messa… Read More

Azure DevOps - Unexpected token The login session is timed out & you need to sign in againAzure Data Factory - Unexpected token This can appear when you are working with a data fact… Read More

A Systematic Approach for ResolutionProblemWhile executing insert statement in MS SQL, you may see the following error,Msg 8152, Level 16, State 30, Line 258String or binary data would be tr… Read More

Cause of the errorWhen you are trying to connect to a MS SQL server database, you can enable windows authentication by setting the option integratedSecurity=true.Error MessageUnable to… Read More

Dell Boomi: Connecting to MS SQL Server Database with Windows Authentication Using SQL ConnectorThere is no straight forward solution to use a Boomi database connector to connect to MSSQL se… Read More

Recently I wanted to set up a Jenkins job in such a way that,It is required to list the current Git branch list in the Job pageAllow the user to specify a branch from the listCapture th… Read More

Recently I wanted to install DotNet SDK in a Ubuntu box. While searching the possibilities, I noticed that there are two ways to follow, the Ubuntu version specific way and the inherite… Read More

IncidentRecently I encountered a build issue in a Jenkins job on a dot net project caused by the Dotnet SDK. The Jenkins environment was set up in an Ubuntu Box.Strangely, this hap… Read More

How to Insert Data to a Table by Selecting from a Different TableIt is often required to insert data in to a table selectively fetching data from a  different table. This is a cruc… Read More

Drop all the tables in a schema in MySQL DatabaseIt is often required to delete tables from a MySQL schema. Following is a simple SQL guide that can be used for deleting the all or the speci… Read More

Hibernate Level 1 CacheHibernate contains a very sophisticated caching mechanism which increases the  performance of the data fetching. Level 1 caching mechanism is… Read More

AWS Guard Duty : Intelligent Threat Detection ServiceAWS Guard Duty is a detection & shielding service that continuously monitor and detects various kind of malicious or unauthorize… Read More

Is it often required to find the exact MySQL version running in a specific system. Specially it is required to check the version incompatibilities before executing any queries or the sc… Read More

Java SE 10 production ready release arrived unnoticed on 20th March 2018.Key Features Local-variable type inference: enhances the Java language to extend type inference to declarations… Read More

JDK - Java Development KitJDK contains the Java development tool kit with the Java Run time Environment. Basically this is required for Java development. Testing & deploym… Read More

While working with developer testing and related stuff, it is often required to update the database schema, use old versions or revert back & forth. However after working with few v… Read More

ZonedDateTime can be converted to Java Date by converting it to an instance first,Date date = Date.from(ZonedDateTime.now().toInstant());https://docs.oracle.com/javase/8/docs/api/java/time/Z… Read More

Git pull request failed when the remote current branch head is different from the local.$ git pullremote: Counting objects: 9115, done.remote: Compressing objects: 100% (46/46), done.remote:… Read More

INSERT IGNORE option by MySQL is a very convenient keyword to gracefully handle an INSERT of a record with an existing Key.The regular INSERT always lead to a Primary Key viol… Read More

In SQL Scripting, it is often required to reuse the queried values, while executing queries in sequence.User defined variables are a good methodology to deal with above situation.SELECT @pub… Read More

INSERT IGNORE option by MySQL is a very convenient keyword to gracefully handle an INSERT of a record with an existing Key.The regular INSERT always lead to a Primary Key viol… Read More

Adding stackoverflow Profile to your blog/ website is very straightforward. All you have to do is to get the profile html snippet from the flair tab as stackoverflow has… Read More

In Operator allows to specify multiple values in where clauseSELECT *FROM booksWHERE ISBN IN (123456, 456789, ...);It also smart enough to support nested queries as well,SELECT *FROM bo… Read More

In Operator allows to specify multiple values in where clauseSELECT *FROM booksWHERE ISBN IN (123456, 456789, ...);It also smart enough to support nested queries as well,SELECT *FROM bo… Read More

It is often required to investigate the queries executed on MySQL Server Log for many reasons when debugging.Specially it allows to see the values passed in for the parameters for… Read More

Exclude Third Party Sources from SonarProject Level ConfigurationThe easiest and the cleanest way to make an exclusion of source files from Sonar scanning is from sonar-project.pro… Read More

Define the variable and set it in the server,SET @country = 'Sri Lanka';SET @section = 'Science Fiction';Now you can write the query with placeholders,SELECT book_name, isbn_number, author_i… Read More

Sonar IssueViolation : Explicitly Import the Specific Classes NeededRule : Wildcard imports should not be usedIntelliJ IDEA Menu NavigationSettings > Editor > Code Style > Java >… Read More

Define the variable and set it in the server,SET @country = 'Sri Lanka';SET @section = 'Science Fiction';Now you can write the query with placeholders,SELECT book_name, isbn_number, author_i… Read More

Cmder - Portable console emulator for WindowsLooking for a nice console emulator on Windows ?Cmder is a software package created out of pure frustration over the absence of nice co… Read More

Replace All Spaces in a Stringtrim()Removes only the leading & trailing spaces.From Java Doc,"Returns a string whose value is this string, with any leading and trailing whitesp… Read More

Exclude Third Party Sources from SonarProject Level ConfigurationThe easiest and the cleanest way to make an exclusion of source files from Sonar scanning is from sonar-project.pro… Read More

Apache Tomcat as a Windows Service & Configure for Remote DebuggingDownload Apache TomcatGo directly to the Apache Tomcat Site, select the version you prefer for download . Select&n… Read More

Multiple Log Files View in a Single Consoletail Multiple Log Files in to a Single Linux Console  You may already know that it is possible to view a log file in Linux by tail comman… Read More

Tail Multiple Log Files in to a Single Linux Console  You may already know that it is possible to view a log file in Linux by tail command.tail command allows to display… Read More

Should we use 200 OK or 204 No Content as per the response for Delete Operation ?It is often arguable whether we should use 200 or 204 as response code.When to use 204204 Definitio… Read More

Free Riding in P2P NetworksFree riding is the process utilising the resources of the peer to peer network without reasonably contributing back to it.P2P system or a peer to peer communicatio… Read More

Effective Java 3rd Edition by Joshua BlochEffective Java 3rd Edition by Joshua Bloch has been released last December (2017) which is targeting Java 7,8 and 9th Versions.The new ver… Read More

Cassandra Query IssueWhen querying for data in Cassandra, The following error was thrown in DataStax Studio,SELECT * FROM XXXXX WHERE name = "xxxxx"line 0:-1 no viable alternative at input '… Read More

The IssueFollowing error can be noticed while using the Spring Data Cassandra, if you need to search between a range on a column where secondary index is set on it.org.springframework.d… Read More

List  List colourList = new ArrayList();  colourList.add("RED");  colourList.add("GREEN");  colourList.add("BLUE");  colourList.add("YELLOW");  colourList.add(… Read More

HTTP PollingHTTP polling is the process of looking for the server by client in pre-defined time intervals to fetch up-to-date information if available. In HTTP polling, client send a request… Read More

Symbolic links, symlinks or soft links are a logical reference created from a file to another file or a folder.Creating a Simlink  ln -s   ln -s /opt/devdummy /data/devdummyThe abo… Read More

When the local git repository is corrupted, the following message will be thrown by git for all type of git commands.error: object file .git/objects/34/a933ab83249282f901d07ff29eb5346f1… Read More

When the local git repository is corrupted, the following message will be thrown by git for all type of git commands.error: object file .git/objects/34/a933ab83249282f901d07ff29eb5346f1… Read More

While querying on Apache Cassandra Database, it can be seen the following error message thrown,Caused by: com.datastax.driver.core.exceptions.InvalidQueryException: Cannot execute this query… Read More

When it is trying to stop Apache Tomcat gracefully, it is often noticed that it starts to hang throwing a error such as follows,org.apache.catalina.startup.HostConfig.deployWARs Error waitin… Read More

When it is trying to stop Apache Tomcat gracefully, it is often noticed that it starts to hang throwing a error such as follows,org.apache.catalina.startup.HostConfig.deployWARs Error waitin… Read More

Cassandra ExceptionIn Spring Data Cassandra integration to the project, you may have setup the cassandra context as follows,           The IssueAnd may sti… Read More

Apache Log4j is a Java-based logging utility. This is a comprehensive guide to integrate log4j in to a java project quickly & easily. Anyway it is a really… Read More

1. List CPU Core Level Information cat /proc/cpuinfo[sdn@devdummy ~]$ cat /proc/cpuinfoprocessor : 0vendor_id : GenuineIntelcpu family : 6model : 58model name : Intel(R) Core(TM) i7-38… Read More

Google PageSpeed Insights is a website analytics tool which helps to optimize the performance and the quality of a web site. First it analyse the web site and then it generates suggestions t… Read More

public static void main(String[]  args)In Java, the execution of an application starts this method, with signature 'public static void main(String[]  args)'It is also sai… Read More

You may have notice the following error while tomcat restart.org.apache.catalina.session.StandardManager.startInternal Exception loading sessions from persistent storage java.io.StreamC… Read More

When you trying to ssh to a AMI (Mostly to an AMI, Amazon instance) using the following command,$ ssh -i key.pem user@hostIt may be showing the above the error@@@@@@@@@@@@@@@@@@@@@… Read More

I found an interesting video session by Joshua Bloch where he serves up a few Java Puzzlers as an appetizer before and as dessert after the main course on Effective Java.Organized By: Silico… Read More

Functional Interfaces, What is that, seriously, in Java?Functional Interface is a new concept introduced from Java 8 which are more focused to towards the new features like Lambda Expression… Read More

In a Spring Data project, if the data seems not being persisted in database using Spring Data Repositories, that is strange but it happens.Surprisingly it never throws an error, even a… Read More

PSQLException: FATAL: sorry, too many clients alreadyImage CreditExceptionCaused by: org.postgresql.util.PSQLException: FATAL: sorry, too many clients already.....Caused by: org.hibernate.ex… Read More

systemctl: command not foundImageWhen you are trying to start a service in Cent OS 6 environment with above command, you may have noticed that the above command is giving an error,$ systemct… Read More

Recently I was looking for an online Favicon designer tool for my devdummy site and fascinated by a simple yet super easy online tool, favicon.cc.Most of the other f… Read More

PostgreSQL : Drop all tables in a schemaDrop & Create The schemaDROP SCHEMA CASCADE;CREATE SCHEMA ;Selectively Delete the tablesSELECT    'drop table if exists… Read More

Quick & simple guide on String Pool concept in JavaImage CreditString Pool in Java corresponds to an allocation of memory in Java heap memory. It consists of a collection of String… Read More

Spring/ Spring Boot Error while running Spring TestsImage Creditjava.lang.IllegalStateException: Failed to load ApplicationContextat org.springframework.test.context.cache.DefaultCacheAwareC… Read More

Quick & Simple method for integrating Maven to Eclipse Image CreditMaven Integration for Eclipse is a really straight forward task through Eclipse Marketplace with the&nbs… Read More

Image Creditorg.springframework.dao.QueryTimeoutExceptionERROR c.a.m.i.api.rest.EventController - Unexpected Errororg.springframework.dao.QueryTimeoutException: java.util.concurrent.TimeoutE… Read More

Lazy Loading vs Eager Loading Image CreditLazy LoadingLazy loading is a design pattern commonly used in computer programming to defer initialization of an object until the point at… Read More

Image CreditWhat is an Immutable Object ?As per the Java Reference Documentation,"An object is considered immutable if its state cannot change after it is constructed"Simply an immutable cla… Read More

Version 4 UUID Generate UUID Read More

Thread SynchronizationJava provides synchronized keyword to provide capabilities on controlling the access to shared resources for multiple threads. However this synchronization ca… Read More

What is a marker interface ?Interface which does not contain any method to implement are called marker or the tag interfaces. Why marker interfaces ?The basic idea of having marker inte… Read More

UUIDsAs per Wikipedia,A universally unique identifier (UUID) is an identifier standard used in software construction. A UUID is simply a 128-bit value. The meaning of each bit is defined by… Read More

Spring framework provide enough flexibility to define the scope of the objects specifically. That means you can define the boundaries of the objects to behave at its creation.1.  … Read More

Static BindingStatic Binding occurs at compile time. Compiler decides the type to be bound in compilation process.Private, final and static methods and variables uses static bindingStat… Read More

The simple rule of thumb here is,".bash_profile is executed for login shells,.bashrc is executed for non-login shells"Login ShellsAs the name says, when you use a login, a username & pas… Read More