Encapsulation wraps data and methods into a single class. Private variables with getters and setters control access.

Definition List

• Encapsulation: Binding data and methods while restricting direct access.
• Data Hiding: Protecting class data by declaring variables private.
• Getter Method: Retrieves the value of a private variable.
• Setter Method: Updates the value of a private variable.
• Private Variable: Accessible only within the declaring class.

How to Achieve Encapsulation

1. Declare class variables as private.
2. Provide getter methods to read data.
3. Provide setter methods to modify data.

Example 01: Getter and Setter Methods

class ShapeRectangle {
    private int length, width;

    int getLength() {
        return length;
    }

    int getWidth() {
        return width;
    }

    void setLength(int l) {
        if (l > 0)
            length = l;
        else
            length = 0;
    }

    void setWidth(int w) {
        if (w > 0)
            width = w;
        else
            width = 0;
    }

    int area() {
        return length * width;
    }
}

public class get_set {
    public static void main(String args[]) {
        ShapeRectangle o = new ShapeRectangle();
        o.setLength(10);
        o.setWidth(20);
        System.out.println("Length : " + o.getLength());
        System.out.println("Width  : " + o.getWidth());
        System.out.println("Area of Rectangle : " + o.area());
    }
}

Output

Length : 10
Width  : 20
Area of Rectangle : 200

Benefits of Encapsulation

• Read-only: provide only getter methods.
• Write-only: provide only setter methods.
• Setters validate data before storing.
• Sensitive data stays private.
• Internal changes don't break external code.

Best Practices

• Always declare variables as private.
• Use getters to read values.
• Use setters to update values.
• Validate input inside setters.
• Never expose sensitive data directly.

FAQ

1. What is encapsulation?

Hiding data and providing access through getters and setters.

2. Why declare variables private?

Prevents direct access and unauthorized modification.

3. What are getter and setter methods?

Getters read private values. Setters update them safely.