//=============================================================================
// Copyright 2006-2010 Daniel W. Dyer
//
// Licensed 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.uncommons.watchmaker.framework.factories;
import java.util.Random;
/**
* General-purpose candidate factory for EAs that use a fixed-length String encoding.
* Generates random strings of a fixed length from a given alphabet.
* @author Daniel Dyer
*/
public class StringFactory extends AbstractCandidateFactory<String>
{
private final char[] alphabet;
private final int stringLength;
/**
* @param alphabet The set of characters that can legally occur within a
* string generated by this factory.
* @param stringLength The fixed length of all strings generated by this
* factory.
*/
public StringFactory(char[] alphabet,
int stringLength)
{
this.alphabet = alphabet.clone();
this.stringLength = stringLength;
}
/**
* Generates a random string of a pre-configured length. Each character
* is randomly selected from the pre-configured alphabet. The same
* character may appear multiple times and some characters may not appear
* at all.
* @param rng A source of randomness used to select characters to make up
* the string.
* @return A randomly generated string.
*/
public String generateRandomCandidate(Random rng)
{
char[] chars = new char[stringLength];
for (int i = 0; i < stringLength; i++)
{
chars[i] = alphabet[rng.nextInt(alphabet.length)];
}
return new String(chars);
}
}