SE450: Taxonomy: Advantages of Immutable Objects [57/63]

Immutable objects do not change.

Aliasing does not matter!

We can freely copy references without fear that the object will change.

This has several corollaries:

• No need to clone an immutable object.
• No need for an exclusive reference (defensive copy) of an immutable object.
• Concurrency presents no difficulties -- see SE552.
• With extra care == and equals are equivalent -- discussed later.

Guideline: make all data classes immutable