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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.commons.text.lookup;
/**
* 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
*/
public interface StringLookup {
/**
* 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"));
*
*
* @param key
* the key to look up, may be null
* @return the matching value, null if no match
*/
String lookup(String key);
}