How to create an immutable class in Java

To create an immutable class, you should consider below points:

• Declare the class as final so that no one will extend the class.
• Declare all the variables in the class as final so that no one can change the value of the variables.
• Declare all variables as private so that others can not access directly.
• Do not write setter methods so that others can not modify the actual value of the variables.
• Write the parameterized constructor.

Example of Immutable Class :

public final class ABC {

    private final int id;
    private final String name;
    private final String address;

    public ABC(int id, String name,String address) {
        this.name = name;
        this.id = id;
        this.address = address;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getAddress() {
        return address;
    }
}

Use of Immutable Class :

class Test
{
    public static void main(String args[])
    {
        ABC abc = new ABC(1,"PQRS", "Pune");
        System.out.println(abc.id);
        System.out.println(abc.name);
        System.out.println(abc.address);
    }
}