Java - Key-Value Decision Making
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What would be the best way to store the following Business Rules in a File so that they can be applied on the input values which would be keys?

Key-INDIA; Value-Delhi.
Key-Australia; Value-Canberra.
Key-Germany, Value-Berlin.

One Solution :- Xml

    <Countries>
      <India>Delhi</India>
      <Australia>Canberra</Australia>
      <Germany>Berlin</Germany>
    </Countries>

As the number of rules are going to be > 1000; implementing it using Map is not possible.

Regards,
Shreyas.