w请使用Jmetal解决一下调度车间问题,给出代码

好的，首先我们需要定义调度车间问题的实体类，包括工件、机器和工序等属性：

public class JobShopProblem {
    private int[][] processingTimes; // 工件在机器上的加工时间
    private int[][] machines; // 工件在机器上的加工顺序
    private int[] machinesCount; // 每个工件需要在多少台机器上加工
    private int jobsCount; // 工件数量
    private int machinesCountMax; // 每个工件最多需要在多少台机器上加工
    private int[] machineOccupancy; // 每个机器的占用情况
    // 省略构造函数和 getter/setter 方法
}

然后我们需要定义目标函数，即最小化完成时间（makespan）：

public class JobShopObjectiveFunction implements ObjectiveFunction<JobShopSolution> {
    @Override
    public void evaluate(JobShopSolution solution) {
        JobShopProblem problem = solution.getProblem();
        int[] completionTimes = new int[problem.getJobsCount()];

        int[][] machines = problem.getMachines();
        int[][] processingTimes = problem.getProcessingTimes();

        for (int i = 0; i < problem.getJobsCount(); i++) {
            for (int j = 0; j < problem.getMachinesCount(i); j++) {
                int machine = machines[i][j];
                int processingTime = processingTimes[i][j];
                int startTime = (j == 0) ? 0 : completionTimes[machines[i][j - 1]];
                completionTimes[machine] = startTime + processingTime;
            }
        }

        int makespan = 0;
        for (int completionTime : completionTimes) {
            makespan = Math.max(makespan, completionTime);
        }
        solution.setObjectiveValue(makespan);
    }
}

接下来是定义解决方案类，我们使用一个二维数组表示一个解决方案，其中第一维表示工件，第二维表示对应的机器和工序：

public class JobShopSolution implements Solution<JobShopProblem> {
    private JobShopProblem problem;
    private int[][] solution; // 工件在机器上的加工顺序

    public JobShopSolution(JobShopProblem problem) {
        this.problem = problem;
        this.solution = new int[problem.getJobsCount()][problem.getMachinesCountMax()];
    }

    // 省略 getter/setter 方法

    @Override
    public JobShopSolution copy() {
        JobShopSolution copy = new JobShopSolution(problem);
        for (int i = 0; i < problem.getJobsCount(); i++) {
            System.arraycopy(solution[i], 0, copy.solution[i], 0, problem.getMachinesCount(i));
        }
        return copy;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < problem.getJobsCount(); i++) {
            sb.append(Arrays.toString(solution[i])).append("\n");
        }
        return sb.toString();
    }
}

最后，我们定义变异操作和交叉操作，这里我们使用经典的交叉操作（PMX）和变异操作（Swap）：

public class JobShopCrossoverOperator implements CrossoverOperator<JobShopSolution> {
    @Override
    public List<JobShopSolution> execute(List<JobShopSolution> parents) {
        JobShopSolution parent1 = parents.get(0);
        JobShopSolution parent2 = parents.get(1);
        JobShopProblem problem = parent1.getProblem();

        int[][] child1 = new int[problem.getJobsCount()][problem.getMachinesCountMax()];
        int[][] child2 = new int[problem.getJobsCount()][problem.getMachinesCountMax()];

        int[] mapping = new int[problem.getJobsCount()];
        for (int i = 0; i < problem.getJobsCount(); i++) {
            int idx1 = -1, idx2 = -1;
            for (int j = 0; j < problem.getMachinesCount(i); j++) {
                if (parent1.getSolution()[i][j] == parent2.getSolution()[i][j]) {
                    child1[i][j] = parent1.getSolution()[i][j];
                    child2[i][j] = parent2.getSolution()[i][j];
                } else {
                    idx1 = j;
                    idx2 = j;
                    for (int k = 0; k < problem.getMachinesCount(i); k++) {
                        if (parent1.getSolution()[i][j] == parent2.getSolution()[i][k]) {
                            idx2 = k;
                            break;
                        }
                    }
                    for (int k = 0; k < problem.getMachinesCount(i); k++) {
                        if (parent2.getSolution()[i][j] == parent1.getSolution()[i][k]) {
                            idx1 = k;
                            break;
                        }
                    }
                    child1[i][j] = parent1.getSolution()[i][idx2];
                    child2[i][j] = parent2.getSolution()[i][idx1];
                }
            }
            mapping[i] = idx1;
        }

        for (int i = 0; i < problem.getJobsCount(); i++) {
            if (mapping[i] != -1) {
                for (int j = 0; j < problem.getMachinesCount(i); j++) {
                    if (child1[i][j] == parent1.getSolution()[i][mapping[i]]) {
                        child1[i][j] = parent2.getSolution()[i][mapping[i]];
                    }
                    if (child2[i][j] == parent2.getSolution()[i][mapping[i]]) {
                        child2[i][j] = parent1.getSolution()[i][mapping[i]];
                    }
                }
            }
        }

        JobShopSolution childSolution1 = new JobShopSolution(problem);
        childSolution1.setSolution(child1);
        JobShopSolution childSolution2 = new JobShopSolution(problem);
        childSolution2.setSolution(child2);
        return Arrays.asList(childSolution1, childSolution2);
    }
}

public class JobShopMutationOperator implements MutationOperator<JobShopSolution> {
    @Override
    public void execute(JobShopSolution solution) {
        JobShopProblem problem = solution.getProblem();

        int i = RandomUtils.nextInt(0, problem.getJobsCount());
        int j = RandomUtils.nextInt(0, problem.getMachinesCount(i));
        int k = RandomUtils.nextInt(0, problem.getMachinesCount(i));

        int temp = solution.getSolution()[i][j];
        solution.getSolution()[i][j] = solution.getSolution()[i][k];
        solution.getSolution()[i][k] = temp;
    }
}

最后，我们可以使用 JMetal 对调度车间问题进行求解：

JobShopProblem problem = new JobShopProblem(/*省略参数*/);
JobShopCrossoverOperator crossoverOperator = new JobShopCrossoverOperator();
JobShopMutationOperator mutationOperator = new JobShopMutationOperator();
ObjectiveFunction<JobShopSolution> objectiveFunction = new JobShopObjectiveFunction();
SelectionOperator<List<JobShopSolution>, JobShopSolution> selectionOperator = new BinaryTournamentSelection<>();
TerminationCriterion terminationCriterion = new StoppingByEvaluations(10000);
Algorithm<List<JobShopSolution>> algorithm = new NSGAIIBuilder<>(problem, crossoverOperator, mutationOperator)
        .setObjectiveFunction(objectiveFunction)
        .setSelectionOperator(selectionOperator)
        .setMaxEvaluations(10000)
        .setPopulationSize(100)
        .build();
algorithm.run();
List<JobShopSolution> solutions = algorithm.getResult();