How can we create our own immutable class?

Immutable class in java means that once an object is created, we cannot change its content. In Java, all the wrapper classes (like Integer, Boolean, Byte, Short) and String class is immutable. We can create our own immutable class as well. Prior to going ahead do go through characteristics of immutability in order to have a good understanding while implementing the same. Following are the requirements: 

• The class must be declared as final so that child classes can’t be created.

• Data members in the class must be declared private so that direct access is not allowed.

• Data members in the class must be declared as final so that we can’t change the value of it after object creation.