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Showing posts from January, 2013

Java Design Patterns : Adapter Pattern

Whenever and wherever you will read about Adapter pattern you will come across example of electric adapters. Be it a 3-pin to 2-pin adapter, round pin to flat pin adapter or AC to DC adapter, its purpose is to act as an intermediary between electrical equipment and the socket.

Above is a representation of a 3-pin to 2-pin adapter which exposes a 3-pin socket which takes in a 3 pin plug and gives a 2 pin output. (These 2-pins can be plugged into any 2-pin socket.) 
Note that the adapter contains a 3-pin plug inside and behavior of its 3 pins is altered to suit the behavior of the adapter pins which will fit in the 2-pin socket.
Now if we interpolate this in terms of Java concepts, the 3-pin socket is an interface and every 3-pin plug implements this interface. Let's call this as 'adaptee' interface. Similarly every 2-pin socket is also an interface which is implemented by every 2-pin plug. Let's call the 2-pin socket (which our adapter is trying to be compatible with) …