What is instantiation and initialization in programming?

Instantiation is the process of creating an instance of a class (object) in memory, allocating space for it, and assigning it a unique identifier.

Initialization is the process of assigning initial values to the object's fields after its creation (instantiation). It is usually performed by the class constructor.

In other words, instantiation is the birth of an object, and initialization is its preparation for work by assigning starting values.

Example in Kotlin:

class Example { // Class
    var value: Int // Class field

    constructor(initialValue: Int) { // Constructor for initialization
        // Instantiation occurs before the constructor is called,
        // but here inside the constructor, the field value is initialized
        this.value = initialValue
    }
}

fun main() {
    // Instantiation and initialization of an Example class object
    val myObject = Example(10) // Constructor is called here
    println(myObject.value) // Output: 10
}

In this example, Example(10) performs both instantiation (creating the myObject object) and initialization (assigning the value 10 to the value field using the constructor).

Comparison:

Process	Description	When does it occur?
Instantiation	Creating an object in memory	When calling the new operator (in Java) or during initialization (in Kotlin)
Initialization	Assigning initial values to the object's fields	Usually inside the constructor after instantiation