Welcome back, Sujit Kumar Mishra

How can you create a custom immutable class? 

An immutable class is a class whose objects cannot be changed after creation. To make a class immutable in Java, follow these simple steps:

1: Make the class final so it cannot be subclassed.

2: Make all fields private and final so they cannot be changed after initialization.

3: Do not provide any setter methods.

4: Initialize all fields via the constructor.

5: If any field is an object, return a copy in the getter method (to prevent changes from outside).

Example:

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

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

Once you create a Person object, you cannot change its name or age, making it immutable.

Key points to remember:

1: Use final for class and fields.

2: Only getters, no setters.

3: All fields set in constructor.