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The James core module is part of the James framework for optimization using local search metaheuristics in Java. The core contains general components to model problems, objectives and constraints, as well as generic algorithms to solve the problems. Moreover, the core provides implementations of specific utilities for subset selection.

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//  Copyright 2014 Herman De Beukelaer
//
//  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.jamesframework.core.search.algo;

import org.jamesframework.core.problems.Problem;
import org.jamesframework.core.problems.solutions.Solution;
import org.jamesframework.core.search.Search;

/**
 * The random search algorithm iteratively samples a random solution and checks
 * whether a new best solution has been found, in every search step.
 * 
 * @param  solution type of the problems that may be solved using this search, required to extend {@link Solution}
 * @author Herman De Beukelaer
 */
public class RandomSearch extends Search {
    
    /**
     * Create a random search, given the problem to solve. Note that problem can not be null.
     * The search name is set to the default name "RandomSearch".
     * 
     * @throws NullPointerException if problem is null
     * @param problem problem to solve
     */
    public RandomSearch(Problem problem){
        this(null, problem);
    }
    
    /**
     * Create a random search, given the problem to solve and a custom search name. Note that problem can
     * not be null. The search name can be null in which case it is set to the default name
     * "RandomSearch".
     * 
     * @throws NullPointerException if problem is null
     * @param problem problem to solve
     * @param name custom search name
     */
    public RandomSearch(String name, Problem problem){
        super(name != null ? name : "RandomSearch", problem);
    }
    
    /**
     * In every search step, a random solution is created and the best solution might be updated accordingly.
     */
    @Override
    protected void searchStep() {
        // sample random solution
        SolutionType sol = getProblem().createRandomSolution();
        // check if new best solution found
        updateBestSolution(sol);
    }

}