The adapter implements an interface to the adaptee and the target

The adapter holds an instance of the adaptee and the interface

The adapter implements the adaptee interface and holds and instance of the target

The adapter implements the target interface and holds an instance of the adaptee

Create a facade to interact with the vendor system

Receive requests from the existing system and convert them into requests for the existing system

Receive requests from the existing system and convert them into requests that make sense to the new vendor class.

Create a facade to interact with the existing system

The client and the target

The client and the adapter

The target and the adpater

The client, the adapter and the target

Always two

An adapter pattern will always be flexible to have multiple adaptees.

Most examples of adapter pattern show an adapter with one adaptee, however you may well have situations where an adapter hold two or more adaptees.

One and only one

Yes but do keep their own internal context

No  since they do not keep their own internal context

Yes but do not keep their own internal context

No since they need keep their own internal context

A new interface

A new action

A new inheritance

A new state

Super calss

Inheritance

Interface

Sub class

All the states

All the interfaces

All the actions

All the static variables

Reduce the number of classes

Only move the classes around

Keep the number of classes the same

Increase the number of classes