Naresh Joshi | The Blog Pros

September 3, 2020

Java Integer Cache: Why Integer.valueOf(127) == Integer.valueOf(127) Is True

According to our calculations, Integer.valueOf(127) == Integer.valueOf(127) is true.

In an interview, one of my friends was asked: If we have two Integer objects, Integer a = 127; Integer b = 127; Why does a == b evaluate to true when both are holding two separate objects? In this article, I will try to answer this question and explain the answer.

You may also like: The Internal Cache of Integers

Short Answer

The short answer to this question is, direct assignment of an int literal to an Integer reference is an example of auto-boxing concept where the literal value to object conversion code is handled by the compiler, so during compilation phase compiler converts Integer a = 127; to Integer a = Integer.valueOf(127);.

November 21, 2019

How Does JVM Handle Polymorphism Internally

How does JVM handle Polymorphism.

You may also like: Everything About Method Overloading vs. Method Overriding

In my previous article, Everything About Method Overloading vs. Method Overriding, I discussed method overloading and overriding, their rules and differences.

In this article, we will see How Does JVM Handle Method Overloading And Overriding Internally, how JVM identifies which method should get called.

August 16, 2019

How to Customize Serialization in Java Using the Externalizable Interface

In a previous article, Everything You Need to Know About Java Serialization Explained, I explained how we can serialize/deserialize one object using the Serializable interface and explain how we can customize the serialization process using writeObject and readObject methods.

Disadvantages of Java Serialization Process

But these customizations are not sufficient because the JVM has full control of the serialization process and those customization logics are just additions to the default serialization process. We still have to use the default serialization logic by calling ObjectOutputStream.defaultWriteObject() and ObjectInputStream.defaultReadObject() from writeObject and readObject methods. And if we do not call these default methods, our object will not be serialized/deserialized.

August 14, 2019

Everything You Need to Know About Java Serialization Explained

In a previous article, we looked at five different ways to create objects in Java, I have explained how deserializing a serialized object creates a new object, and in this blog, I am going to discuss Serialization and Deserialization in details.

We will use below Employee class object as an example for the explanation

August 12, 2019

5 Different Ways to Create Objects in Java

Being Java developers, we usually create lots of objects daily, but we always use dependency management systems e.g. Spring to create these objects. However, there are more ways to create objects, which we will study in this article.

There are five total ways to create objects in Java, which are explained below with their examples followed by bytecode of the line which is creating the object.

January 30, 2019

Useful Git Commands

Git is a most widely used and powerful version control system for tracking changes in computer files and coordinating work on those files among multiple people. It is primarily used for source code management in software development, but it can be used to keep track of changes in any set of files.

Git was developed by Linus Torvalds in 2005 as an distributed open source software version control software and of course it is free to use. As a distributed revision control system it is aimed at speed, data integrity, and support for distributed, non-linear work flows.