Difference between Getter setter methods and constructor in java

<<–2/”>a href=”https://exam.pscnotes.com/5653-2/”>p>getter/setter methods, constructors in Java, along with their differences, advantages, disadvantages, similarities, and FAQs.

Introduction

In object-oriented programming (OOP), the principles of encapsulation and data hiding are paramount. Java provides constructs like constructors, getters, and setters to help you manage access to the internal state of your objects, ensuring the Integrity and consistency of your data.

Constructors: Special methods called when you create an object (an instance of a class). Their primary role is to initialize the object’s fields (variables) with appropriate values.

Getters (Accessors): Methods designed to retrieve the value of a private field. They provide a safe way to read the object’s state without allowing direct modification.

Setters (Mutators): Methods designed to modify or update the value of a private field. They allow controlled changes to the object’s state while maintaining data integrity.

Key Differences (Table Format)

Feature	Constructor	Getter (Accessor)	Setter (Mutator)
Purpose	Initializes objects	Retrieves field values	Modifies field values
Return Type	None (not even void)	Same as the field’s data type	Usually void
Naming Convention	Same as the class name	Starts with “get” + field name	Starts with “set” + field name
Invocation	Automatic when object is created	Explicitly called on the object	Explicitly called on the object
Overloading	Yes	No	No
Overriding	No	Yes (if the field is inherited)	Yes (if the field is inherited)

Advantages and Disadvantages

Constructors

Advantages:

• Ensure objects are initialized with valid data upon creation.
• Can have multiple constructors for flexibility (overloading).
• Make code more readable by centralizing initialization logic.

Disadvantages:

• Cannot be called directly after object creation to re-initialize.
• Overloading can lead to complex code if not used judiciously.

Getters and Setters

Advantages:

• Encapsulate data and control access to fields.
• Enable data validation and additional logic during setting.
• Provide a flexible way to work with object state.
• Can be overridden in subclasses to customize behavior.

Disadvantages:

• Can add boilerplate code (though IDEs often automate generation).
• Excessive use might hinder performance in rare cases.

Similarities

• All three are member methods of a class.
• Contribute to the principles of encapsulation and data hiding.
• Can be used to manage object state effectively.

FAQs

1. When should I use a constructor vs. a setter?

• Constructor: For mandatory initial values or when you want to prevent an object from being created in an invalid state.
• Setter: For optional values, values that might change over time, or when you want to provide fine-grained control over how the value is set.

2. Can I have multiple constructors in a class?

• Yes, you can overload constructors by having different parameter lists. This provides flexibility when creating objects.

3. Should I always provide getters and setters for every field?

• No, only provide them for fields you intend to expose outside the class. Some fields might be purely internal for calculations and don’t need accessors/mutators.

4. What if I want to prevent a field from being modified after object creation?

• Omit the setter method for that field. This makes the field effectively “read-only” after initialization.

5. How do getters and setters relate to the concept of immutability?

• Immutable objects cannot be changed after creation. To create immutable objects, you would typically initialize all fields via the constructor and provide getters but no setters.

Code Example:

public class Person {
    private String name;
    private int age;

    // Constructor
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    // Getter for name
    public String getName() {
        return name;
    }

    // Setter for name
    public void setName(String name) {
        this.name = name;
    }

    // Getter for age
    public int getAge() {
        return age;
    }

    // Setter for age (with validation)
    public void setAge(int age) {
        if (age >= 0) {
            this.age = age;
        } else {
            System.out.println("Invalid age. Age cannot be negative.");
        }
    }
}