public abstract class StrLookup extends java.lang.Object
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.
This class comes complete with various factory methods. If these do not suffice, you can subclass and implement your own matcher.
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
|Modifier and Type||Method and Description|
Looks up a String key to a String value.
Returns a lookup which looks up values using a map.
Returns a lookup which always returns null.
Returns a lookup which uses
public static StrLookup noneLookup()
public static StrLookup systemPropertiesLookup()
System propertiesto lookup the key to value.
If a security manager blocked access to system properties, then null will be returned from every lookup.
If a null key is used, this lookup will throw a NullPointerException.
public static StrLookup mapLookup(java.util.Map map)
If the map is null, then null will be returned from every lookup. The map result object is converted to a string using toString().
map- the map of keys to values, may be null
public abstract java.lang.String lookup(java.lang.String key)
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.
lookup(String) method always returns a String, regardless of
the underlying data, by converting it as necessary. For example:
Map map = new HashMap(); map.put("number", new Integer(2)); assertEquals("2", StrLookup.mapLookup(map).lookup("number"));
key- the key to be looked up, may be null
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