How Does Java Initialize Classes and Objects, and What's the Order of Initialization?

Java Order of Initialization and Instantiation

Classes and objects in Java undergo distinct initialization processes that play a crucial role in the language's execution. This article aims to clarify and elaborate on the concepts of initialization and instantiation, addressing specific questions and resolving the complexities often encountered in the Java Language Specification (JLS).

Class Initialization

Class initialization occurs during the first access to a class or interface, involving several steps:

1. Assigning constant static fields.
2. Recursively initializing the superclass (if required).
3. Processing static initializers and setting non-constant static field values.

Interfaces are initialized separately, typically when non-constant interface fields are accessed. This initialization can trigger recursive behaviors.

Object Initialization

When an object is created, object initialization takes place, comprising the following actions:

1. Parameter assignment for constructor invocation.
2. Calling the constructor of the same class (if present).
3. Invoking the superclass constructor (if any).
4. Executing instance initializers and variable assignments in sequential order.
5. Executing the remaining constructor body.

Answers to Questions

1. Interfaces are processed in the order of their declaration within the class.
2. No, interfaces are not processed in a separate recursive stack.
3. a) Interfaces get processed first, followed by the superclass.
   b) Static non-compile-time constant fields of interfaces are initialized before the compile-time constant fields of the superclass.
4. The call to the nondefault super() constructor triggers the initialization of the superclass constructor and its subsequent steps.
5. No major mistakes in your conclusions were identified.
6. You highlighted the key details efficiently.

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