Difference between var, val, and def in Scala

This is one of the frequently asked questions from Scala interviews. Even though both var and val keyword is used to declare variables in Scala there is a subtle difference between them. A var is a variable. It’s a mutable reference to a value. Since it’s mutable, its value may change through the program lifetime. On the other hand, val keyword represents a value. It’s an immutable reference, meaning that its value never changes. Once assigned it will always keep the same value. It’s similar to a final variable in Java or constants in other languages. It's also worth to remember that the variable type cannot change in Scala. You may say that a var behaves similarly to Java variables.

How to convert JSON String to Java Object - Gson/JSON Deserialization Example

In the last article, you have learned how to convert a Java object to JSON String and in today's article, you will learn the opposite, i.e. converting a JSON String to Java object. The first example was known as JSON serialization example and this one is known as JSON deserialization because we are creating a Java object from a String. The idea is very similar to classical Serialization in Java where you convert a Java object to another binary format which can be transported over the network or can be saved in the disk for further usage. That's why the process of converting a Java object to JSON is known as serialization and converting a JSON document to Java object is known as De-Serialization. You can use any JSON library to perform serialization and de-serialization e.g. Jackson Databind, Gson, or Json-simple.  In this program, I'll show you how to use Gson to create a Java object from given JSON String.

How to convert Java object to JSON String - Gson Java/JSON Serialization Example

If you are a Java or Android developer and learning JSON to support JSON format for your project and looking for a quick and simple way to convert your Java object into json format then you have come to the right place. In this article, I'll teach you how to convert a Java object to JSON document using Google's Java library called Gson. This library allows you to convert both Java object to JSON String and a JSON document to Java object. So, let's first do some serialization. Serialization in the context of Gson means mapping a Java object to its JSON representation. In the real world, the data can be really complex with lots of attributes and nested with composed object but for now, we'll start with a class which just contain few value attributes e.g. String, int and boolean.