Getters and Setters

Getters and Setters

Getters and setters provide controlled access to private class attributes, implementing encapsulation. A getter retrieves attribute values, while a setter modifies them. They serve as a protective interface between an object's internal state and external code.

Core Concept

Getters and setters enable validation, data transformation, logging, and other operations when attributes are accessed or modified. This prevents direct access to internal state, maintaining object integrity and allowing classes to enforce business rules.

Access Control Flow

graph LR
    A["Client Code"] --> B["Getter/Setter Method"]
    B --> C["Validation & Processing"]
    C --> D["Private Attribute"]

    style A fill:#e8f5e8
    style B fill:#c8e6c9
    style C fill:#fff3e0
    style D fill:#e3f2fd

This diagram shows how client code accesses private attributes through controlled methods that can validate and process data.

Benefits of Getters and Setters

graph TD
    A["Getters & Setters"] --> B["Data Validation"]
    A --> C["Access Control"]
    A --> D["Computed Properties"]
    A --> E["Logging & Monitoring"]
    A --> F["Business Rules"]

    style A fill:#e8f5e8
    style B fill:#c8e6c9
    style C fill:#ffcdd2
    style D fill:#e3f2fd
    style E fill:#fff3e0
    style F fill:#f3e5f5

This diagram illustrates the key benefits that getters and setters provide in object-oriented programming.

Implementation Examples

Let's explore how different programming languages implement these controlled access mechanisms:

JavaKotlinTypeScriptDartSwiftPython

public class Guitar {
    private String brand;
    private double price;

    public Guitar(String brand, double price) {
        this.brand = brand;
        this.price = price;
    }

    // Getter
    public String getBrand() {
        return brand;
    }

    // Setter with validation
    public void setPrice(double price) {
        if (price > 0) {
            this.price = price;
        }
    }
}

// Usage
Guitar guitar = new Guitar("Fender", 1000.0);
System.out.println(guitar.getBrand());  // Fender
guitar.setPrice(1500.0);  // Valid price
guitar.setPrice(-100);    // Ignored (validation)

class Guitar(private var _brand: String, private var _price: Double) {
    // Custom getter
    val brand: String
        get() = _brand.uppercase()

    // Custom setter with validation
    var price: Double
        get() = _price
        set(value) {
            if (value > 0) _price = value
        }
}

// Usage
val guitar = Guitar("Fender", 1000.0)
println(guitar.brand)  // FENDER (uppercase)
guitar.price = 1500.0  // Valid
guitar.price = -100    // Ignored

class Guitar {
    private _brand: string;
    private _price: number;

    constructor(brand: string, price: number) {
        this._brand = brand;
        this._price = price;
    }

    // Getter
    get brand(): string {
        return this._brand;
    }

    // Setter with validation
    set price(value: number) {
        if (value > 0) {
            this._price = value;
        }
    }
}

// Usage
const guitar = new Guitar("Fender", 1000.0);
console.log(guitar.brand);  // Fender
guitar.price = 1500.0;      // Valid
guitar.price = -100;        // Ignored

class Guitar {
    String _brand;
    double _price;

    Guitar(this._brand, this._price);

    // Getter
    String get brand => _brand;

    // Setter with validation
    set price(double value) {
        if (value > 0) _price = value;
    }
}

// Usage
Guitar guitar = Guitar("Fender", 1000.0);
print(guitar.brand);  // Fender
guitar.price = 1500.0;  // Valid
guitar.price = -100;    // Ignored

class Guitar {
    private var _brand: String
    private var _price: Double

    init(brand: String, price: Double) {
        self._brand = brand
        self._price = price
    }

    // Getter
    var brand: String {
        return _brand
    }

    // Setter with validation
    var price: Double {
        get { return _price }
        set {
            if newValue > 0 {
                _price = newValue
            }
        }
    }
}

// Usage
let guitar = Guitar(brand: "Fender", price: 1000.0)
print(guitar.brand)  // Fender
guitar.price = 1500.0  // Valid
guitar.price = -100    // Ignored

class Guitar:
    def __init__(self, brand, price):
        self._brand = brand
        self._price = price

    @property
    def brand(self):
        return self._brand

    @property
    def price(self):
        return self._price

    @price.setter
    def price(self, value):
        if value > 0:
            self._price = value

# Usage
guitar = Guitar("Fender", 1000.0)
print(guitar.brand)  # Fender
guitar.price = 1500.0  # Valid
guitar.price = -100    # Ignored