It's all about Java

 Write code or write code in right way... Writing a coding solution to a problem can be done in many ways. If the solution can be obtained with less number of code lines, then it is easy to understand and maintain. But what if code is large with having millions of lines. Moreover maintenance and readability becomes difficult as the code base grows... Right?  In this blog I want to share my views and experiences on writing code efficiently and effectively with less maintenance efforts. Aspects to consider while coding: Naming convention Cyclomatic Complexity SOLID principles DRY Principle Managing dead code Comments Naming conventions: Every programming language mandates few norms in order to name variables, classes and functions etc. For ex: Java uses class names first letter to be a alphabet and rest to be lower case letters.  But if we dig little bit more, naming conventions are not limited to only upper case or lower case letters and using alphanumeric letters etc. Nam...

Consider Below points before choosing List concrete implementations for your use case:  ArrayList is a linear data structure and  re-sizable/dynamic array   Initial size can be given. and if not given the default size is 10   It is always good practice to give initial size and advised not to give very large number as size   Good programmers prefer ArrayList to LinkedList if retrieval operations is done more frequently than insertion and deletions of elements.   Better choose LinkedList if insertion and deletion operations are done frequently compared to retrieval operations.   Lists are not sorted. if required use Collections.sort() to sort   Collections.sort() uses optimized merge sort [tim sort] on ArrayList   However legacy merge sort also can be used using a switch. But it is going to be deprecated  in near future  The major difference between ArrayList and LinkedList is RandomAccess behavior...

 Atomicity with Java What is Atomicity Atomicity, in computer science, is considered to be a property [ALL-OR-NOTHING], that the state of a resource in an operation is not controlled by a different flow of execution at the same time [Even in time slicing operations] We know, Java is not pure object oriented programming language, due to primitive data types' design behavior. Most of the Java experts, while designing and developing applications thrives hard, to create, most secured applications considering " Atomicity in multi threaded application". Does Java language helps in developing Secured application..? The answer is no, Java programming language does not give secured applications at all, especially in multi threaded environment. As we know, Java supports 2 types of variables/data types.  Primitive data types User defined data types Primitive data types:       Java supports 8 different primitive data types. They are:   boolean    1 ...

File Management in OS File management includes files and folders creation, copy and paste operations, reading the file and writing into files and deleting the files and folders  And also reading meta data about files and folders. It may include file free space, occupied space and read/write permissions etc. These above operations are considered as file management and managed by respective operating system. GUI that represents Windows File Manager File Management with Java  Though Java is platform independent, programming language depends on native file IO resources of operating system. This is possible with the Java API support. These API are categorized into 2 types. Readers and Writers: Readers and writers does the IO operations, character by character InputStream and OutputStream: Where as InputStream and OutputStream does IO operations byte by byte Below are simple Java programs that demonstrates different File IO operations. Program for creating directory package com.all...

NullPointerException causes and reasons Since Java is object oriented programming language, every thing is considered to be an object. and there is always a scope of an object to be null or "No value".  Since Java supports primitive data types, Java is not considered to be pure Java object oriented programming language.   Few Notable points about NullPointerException NullPointerExceptions is unchecked exception Please read post  Exception handling and java keywords before reading this article Usually if program tries to fetch the value from reference and finds nothing as value, then program throws NullPointerException 'Zero' is not null And empty String is not considered to be null It is not the subclass of RuntimeException class Demo code that throws NullPointerException  package com.allabtjava.blog; public class DemoNullPointerException { class BeanDemo { String name; Integer ID; public String getName() { return name; } public void s...

Evolution of Java: First of all, The Java programming language and it's tools that we currenly using is not what actually expected. This language started as a project to give solutions for embedded devices, mobile phones and other portable peripherals.  Initially, the Java was called Oak.  Why it is Oak first..? and Why it transformed to Java..? The team of five technocrats including Dr. James Gosling and also known as Dr. Java, together working on a project, which expected to give solutions on embedded devices, portable smart devices and TV Set top Boxes etc. at Sun Micro Systems.  In the process of achieving this solution, at their breaktime, team used to relax with a coffee by having a glimpse on a scenery of Oak tree next to their facility.  Once the project has come to conclusion and in the process of giving a title to it, they noticed the Oak trees [Always observing them in their break time], they named this programming language as Oak. Oak Logo Why it transfor...

IDE: Integrated Development Environment Integrated development environment, in short IDE is a convenient environment to write, execute and  debug the code or programs on a single platform. IDEs support not only writing code smoothly but also provides a provision to write scripts, XML files, simple text files and build scripts like Ant, Maven are few among others. In short IDEs are development environments to execute complete development activities using one application. IDEs and Editors IDEs and Editors fulfills the same purpose. That is writing code. But IDEs are glued or closely works with respective programming language's compilers, runtime environments, profilers and other language specific tools to put developer in a comfortable zone.  Some of the features of IDE: Auto completion Syntax Highlighting Code debugger Profilers Multipage editors Auto completion: Auto completion feature suggests APIs [methods, classes and interfaces] and keywords etc as we start typing in the e...

First of all, please read below blog post to understand basics of Exception Handling in java. Exception handling and java keywords To continue from there, Basically Java default API has hierarchy of  java classes to support different uses cases of exceptions.  The parent class of all Exceptions and Errors is Throwable . Please check below pictorial representation of  API Hierarchy. Exception: The class Exception and any subclasses that are also not subclasses of RuntimeException are checked exceptions. And all subclasses of RuntimeException and RuntimeException class itself are Unchecked exception . Rest all are Checked exceptions Examples of Unchecked Exceptions:            ArrayIndexOutOfBoundException          NullPointerException Error: An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch. Most such errors are abnormal conditions. Examples: T...

Unlike AWT, Java Swing tool kit provides feasibilty to create custom components and containers. To understand Java GUI toolkits more clearly, please read my other articles on Swing and AWT.  In this article I focus more on building custom components. Let us see how to create simple Rounded JButton. The below program demonstrates How rounded JButton can be created and added to a JFrame.   Program: import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.GridLayout; import java.awt.Shape; import java.awt.geom.Ellipse2D; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JTextField; import javax.swing.SwingUtilities; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class RoundedJButton extends JButton { /** *  */ private static final long serialVersionUID = 1L; public RoundedJButton(String title) { super(title); Dimension size = getPreferredSize(); size.w...

Exception: Exception in a programming language and in English language is pretty similar. Exception means being different from or not following the rules. And in programming language like Java, exception is  an event which occurs during the execution of a program that disturbs the complete flow of application or program. When something beyond expected happens while executing a program is considered as an error. handling these errors or abnormality is called as Exception handling. Exception Handling: Exception handling in java is managed with the help of java keywords and java API support..              1. Java Keywords             2. Java API support Java Keywords:   There are 5 keywords in Java.           1. Try           2. catch           3. finally           4. throw    and 5. throws These five keywor...

Java is an object oriented programming language which can be downloaded and installed in your local Machine from java.com To explain java binaries and tools requires block diagram which gives clear picture. For now I brief few important tools. JDK - java development toolkit JVM - Java virtual machine JRE - Java Run time environment From oracle site we can download JDK which is shipped along with JVM and JRM. Mostly java programmers need the JDK. For end users JRE alone is enough. Basic OOPS characteristics are Inheritance Encapsulation Abstraction and Polymorphism The above concepts collectively makes application software extendable and changeable with less effort. Also helps in Developing design patterns. Design patterns gives solutions for common challenges usually a programmer faces while development applications. Factory design pattern, Abstract design pattern, Builder pattern etc. I explain these Design patterns in another article. Inheritance : Inherita...

Immutable objects and mutable objects with an example  In object oriented programming language, in short OOPS, every problem, precisely every requirement is viewed as an object. Understanding the problem in this point of view brings many good things possible in programming like encapsulation, abstraction, polymorphism and inheritance. Anyways this post is not intended for describing benefits of OOPS. Object could be any thing. Let us take Car  for an instance. Basically car is an object and it has name, wheels, metal body, engine, maximum speed,  gear box etc as properties. Let us consider the car name is Ferrari, maximum speed is 200 km per hr with 6 gears. While driving the car driver can change the speed of the car and change the gear etc. So while car is running it's current speed, current gear are considered to be state of the object. The current speed can be changed using accelerator and gear can be changed using gear box. These can be considered as ...