What is encapsulation in C#, and how would you use it to prevent an Order from entering an invalid state?

Encapsulation and protecting object invariants

Uses controlled state transitions and intention-revealing APIs to keep objects valid rather than treating encapsulation as private fields alone.

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Encapsulation means the Order controls access to its state so callers cannot bypass its rules. I would avoid public setters for state that has business rules. The Order can expose read-only state and methods such as AddItem, Confirm, or Cancel that validate the current state and either complete a valid transition or return a clear failure. Construction should also create a valid Order, so callers cannot bypass rules through an incomplete object initializer.

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Information hiding, invariant protection, accessors, behavior methods, constructors, valid transitions, and persistence boundaries.

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Encapsulation means an object controls how its state is observed and changed. Private fields are a mechanism; preserving the object's rules is the purpose.
Encapsulation means the Order controls access to its state so callers cannot bypass its rules. I would avoid public setters for state that has business rules. The Order can expose read-only state and methods such as AddItem, Confirm, or Cancel that validate the current state and either complete a valid transition or return a clear failure. Construction should also create a valid Order, so callers cannot bypass rules through an incomplete object initializer.
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The method API should express intent rather than expose a sequence of low-level mutations. Confirm can calculate or verify required totals, record the transition, and prevent a second confirmation. Collections can be exposed as read-only views while mutation stays inside the object. Persistence materialization may need private setters or backing fields, but application code should still use the behavioral API.

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Defining encapsulation only as making fields private.
Exposing public setters for every business property.
Allowing object initializers to create invalid instances.
Putting database and HTTP calls inside the entity.

What is encapsulation in C#, and how would you use it to prevent an Order from entering an invalid state?

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