Constructor vs. Method — What's the Difference?
By Tayyaba Rehman & Fiza Rafique — Updated on May 13, 2024
A constructor initializes a new object with specific properties, while a method performs operations on an object's data or behavior.
Difference Between Constructor and Method
Table of Contents
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Key Differences
Constructors are special functions in object-oriented programming used exclusively to create and initialize objects when they are instantiated. In contrast, methods are functions defined within a class that outline behaviors for the objects, which can be invoked to perform actions.
While constructors are called automatically when a new object is created, usually not returning any value, methods can be called anytime using an object's reference and can return values.
A constructor must have the same name as the class in which it resides and does not have a return type. On the other hand, methods can have any name and must specify a return type, even if it is void, indicating no value is returned.
The primary role of a constructor is to allocate memory for the object and initialize each instance variable to default or given values. Methods, however, manage and manipulate these instance variables, providing functionality beyond initialization.
Constructors cannot be inherited, meaning they are not passed down to subclasses; however, methods can be inherited and overridden in subclasses, allowing for polymorphic behavior.
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Comparison Chart
Purpose
Initializes a new object
Performs operations on objects
Invocation
Automatically at object creation
Manually via object reference
Name
Must match the class name
Can be any valid identifier
Return Type
None (not even void)
Specified, can be void or any data type
Inheritance
Not inherited
Can be inherited and overridden
Compare with Definitions
Constructor
Does not return a value and matches the class name.
The 'Book' class has a constructor named 'Book' that sets up the title and author.
Method
Can be called at any point using an object's reference to perform actions.
After creating a 'Car', calling car.start() to begin driving.
Constructor
A special function in a class that initializes new objects.
The constructor for the 'Car' class sets the initial speed and color of the car.
Method
Functions defined within a class that operate on the objects' data.
The 'display' method in the 'Car' class shows the car's current status.
Constructor
Cannot be inherited by subclasses.
Each subclass of 'Vehicle' needs to define its own constructor.
Method
Must have a return type specified, which can be any data type.
The 'getAuthor' method in a 'Book' class returns the name of the author.
Constructor
To form by assembling or combining parts; build.
Method
Can be inherited and overridden in subclasses.
The 'calculateArea' method in 'Shape' can be overridden in 'Circle' subclass.
Constructor
To create (an argument or a sentence, for example) by systematically arranging ideas or terms.
Method
Provides the behaviors of the objects of a class.
The 'updatePassword' method allows a 'User' object to change its password.
Constructor
(Mathematics) To draw (a geometric figure) that meets specific requirements.
Method
A means or manner of procedure, especially a regular and systematic way of accomplishing something
A simple method for making a pie crust.
Mediation as a method of solving disputes. See Usage Note at methodology.
Constructor
Something formed or constructed from parts.
Method
Orderly arrangement of parts or steps to accomplish an end
Random efforts that lack method.
Constructor
A concept, model, or schematic idea
A theoretical construct of the atom.
Method
The procedures and techniques characteristic of a particular discipline or field of knowledge
This field course gives an overview of archaeological method.
Constructor
A concrete image or idea
"[He] began to shift focus from the haunted constructs of terror in his early work" (Stephen Koch).
Method
Method A technique of acting in which the actor recalls emotions and reactions from past experience and uses them in identifying with and individualizing the character being portrayed.
Constructor
A person who, or thing that, constructs.
Method
A process by which a task is completed; a way of doing something (followed by the adposition of, to or for before the purpose of the process).
If one method doesn't work, you should ask a friend to help you.
Constructor
(automotive) A company or individual who builds racing vehicles. In Formula One, constructor status is strictly defined by the rules, but in other motorsports the term is merely a descriptor. Depending on the racing rules, some constructors (e.g. Cosworth) may provide vehicles to racing teams who are not themselves constructors, while others are both teams and constructors (Ducati Corse, Scuderia Ferrari).
Method
A technique for acting based on the ideas articulated by Konstantin Stanislavski and focusing on authentically experiencing the inner life of the character being portrayed.
Constructor
(object-oriented programming) A class method that creates and initializes each instance of an object.
Method
(object-oriented) A subroutine or function belonging to a class or object.
Constructor
A constructer.
Method
(slang) Marijuana.
Constructor
Someone who contracts for and supervises construction (as of a building)
Method
(dated) An instruction book systematically arranged.
Constructor
Called automatically when an object is instantiated.
When a new Car is created, its constructor initializes all necessary components.
Method
Ellipsis of method air.
Constructor
Essential for setting initial state of an object.
The constructor of a 'User' object sets the username and password fields.
Method
(transitive) To apply a method to.
Method
To apply particular treatment methods to (a mold).
The company employs extensive use of 3D modelling combined with solidification simulation to ensure that critical castings are properly methoded.
Method
An orderly procedure or process; regular manner of doing anything; hence, manner; way; mode; as, a method of teaching languages; a method of improving the mind.
Method
Orderly arrangement, elucidation, development, or classification; clear and lucid exhibition; systematic arrangement peculiar to an individual.
Though this be madness, yet there's method in it.
All method is a rational progress, a progress toward an end.
Method
Classification; a mode or system of classifying natural objects according to certain common characteristics; as, the method of Theophrastus; the method of Ray; the Linnæan method.
Method
A technique used in acting in which the actor tries to identify with the individual personality of the specific character being portrayed, so as to provide a realistic rendering of the character's role. Also called the Method, method acting, the Stanislavsky Method or Stanislavsky System.
Method
A way of doing something, especially a systematic way; implies an orderly logical arrangement (usually in steps)
Common Curiosities
What is a method?
A method is a function defined within a class that outlines behaviors for the objects.
Can a constructor return a value?
No, constructors do not return values; they are used only for initialization.
How does a constructor differ from a method?
Constructors initialize objects and are called automatically, whereas methods perform operations and are called manually.
What are the key purposes of methods in object-oriented programming?
Methods provide functionality for objects, such as performing tasks and manipulating data.
What does it mean for a method to be overridden?
Overriding a method means providing a new implementation of the method in a subclass, replacing the superclass's version.
Can methods be static, and what does that mean?
Yes, methods can be static, meaning they belong to the class rather than any instance of the class and can be called without creating an object.
How do constructors and methods contribute to encapsulation?
Constructors set initial state safely, while methods ensure that object manipulation respects the class's intended design, both safeguarding data integrity.
Are constructors required in all classes?
While not strictly required if no initial setup is needed, constructors are generally used to ensure all objects start in a valid state.
What is a constructor?
A constructor is a special function in a class used to initialize new objects.
Why can't constructors be inherited?
Constructors are specific to the class they are defined in and are not meant to be inherited because each class may require different initialization.
What is the difference between a constructor and a factory method?
A constructor is used to create and initialize objects directly, while a factory method is a method that returns an instance of a class, often providing additional logic before object creation.
When should a method be used instead of a constructor?
A method should be used when you need to perform operations or computations on existing objects, beyond just initializing them.
What happens if a constructor is not defined in a class?
If a constructor is not explicitly defined, most programming languages provide a default constructor that initializes object fields to default values.
Can a method change an object’s internal state?
Yes, methods often change an object's state by modifying its fields or properties.
What is constructor chaining?
Constructor chaining refers to a scenario where one constructor calls another constructor within the same class using different parameters.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
Co-written by
Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
