Q.What is encapsulation? Explain how making a field private with public getter and setter methods protects an object's data, with a short example.

Encapsulation bundles data with its methods and hides the data, so all access happens through code the class controls.

Meaning. Encapsulation is one of the core ideas of object-oriented programming. It means keeping the data (fields) and the code that operates on it (methods) together inside one class, and hiding the data from the outside world so it cannot be misused.

The standard technique has two steps:

1. declare the fields private so no outside code can touch them, and
2. provide public methods — a getter to read a field and a setter to change it — so every access passes through code the class controls.

Example:

class Account {
    private double balance;               // hidden data

    public double getBalance() {          // getter: read only
        return balance;
    }

    public void deposit(double amount) {  // setter with a rule
        if (amount > 0) {                 // reject invalid values
            balance = balance + amount;
        }
    }
}

How it protects the data. Because balance is private, code elsewhere cannot write a.balance = -5000; — the compiler forbids it. The only way to change the balance is through deposit(...), which refuses a negative amount. So the object can never be left in an invalid state.

Extra benefit. If the rule changes later (say a deposit must be at least ₹100), you edit only the deposit method and the whole program obeys the new rule — because nothing else was ever allowed to touch balance.

Making the fields public and calling it encapsulation — public fields defeat the purpose because anyone can change them directly. Forgetting to put the validation rule inside the setter, which then gives no protection over a public field.