org.apache.commons.text.lookup

## Interface StringLookup

- All Known Implementing Classes:
    StrLookup

      public interface StringLookup

  Lookups a String key for a String value.

  This class represents the simplest form of a string to string map. It has a benefit over a map in that it can create the result on demand based on the key.

  For example, it would be possible to implement a lookup that used the key as a primary key, and looked up the value on demand from the database.

  Since:
    1.3

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `String` | `lookup(String key)` Looks up a String key to a String value.

- - ### Method Detail

    - #### lookup

          String lookup(String key)

      Looks up a String key to a String value.

      The internal implementation may use any mechanism to return the value. The simplest implementation is to use a Map. However, virtually any implementation is possible.

      For example, it would be possible to implement a lookup that used the key as a primary key, and looked up the value on demand from the database Or, a numeric based implementation could be created that treats the key as an integer, increments the value and return the result as a string - converting 1 to 2, 15 to 16 etc.

      This method always returns a String, regardless of the underlying data, by converting it as necessary. For example:

           Map<String, Object> map = new HashMap<String, Object>();
           map.put("number", new Integer(2));
           assertEquals("2", StringLookupFactory.mapStringLookup(map).lookup("number"));

      Parameters:
        `key` - the key to look up, may be null
      Returns:
        The matching value, null if no match

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