Question

我正在尝试为调度问题创建禁忌搜索算法。变量“Initialsequence”（声明为static）在从其他方法调用时将其值重置为null。 “Initialsequence”中的值填充在方法“CreateInitialSolution（）”中，当我尝试在另一个方法“Create Neighborhood Solution（）”中使用它时，该值为null。你能告诉我为什么吗？

namespace TEST_CODE
{
    class Program
    {
        #region Parameters
        public static int No_mc;
        public static int No_prod;
        public static int Max_jobs;
        public static int[] No_jobs;
        public static int Tot_jobs;
        public static double[,] Run_time;
        public static double[, ,] Setup_time;
        public static double[] Setupst_time;
        public static double[,] Due_time;
        public static double[] Mc_avail_time;
        public static double[,] Job_release_time;
        public static int[] No_storage;
        public static double[] wt_product;
        public static double wt_producer;
        public static double wt_customer;
        public static double[][] tempDue_time;
        public static batch[,] Initialsequence;
        public static int BigM = 10000;

        #endregion Variables

        public class batch
        {
            public int Family { get; set; }
            public int Job { get; set; }
            public batch(int family, int job)
            {
                Family = family;
                Job = job;
            }
        }

 public static void CreateInitialSolution()
        {
            // CreateInitialSolution        
            int[] sequence = new int[Tot_jobs + 1];
            batch[,] Initialsequence = new batch[No_mc + 1, Tot_jobs + 1];

            for (int i = 0; i < Tot_jobs; i++)
            {
                var min = tempDue_time.SelectMany((subArr, k) => subArr.Select((value, j) => new { k, j, value }))
                        .OrderBy(x => x.value)
                        .First();
                int firstIndex = min.k;
                int secondIndex = min.j;
                Initialsequence[1, i + 1] = new batch(firstIndex + 1, secondIndex + 1);
                tempDue_time[firstIndex][secondIndex] = BigM;
            }

            for (int i = 2; i <= No_mc; i++)
            {
                for (int j = 1; j <= Tot_jobs; j++)
                {
                    Initialsequence[i, j] = Initialsequence[1, j];
                }
            }
        }

public static void CreateNeighborhoodSolution() 
        {
            // Create Neighborhood solution
            List<batch[,]> NSJ = new List<batch[,]>();

            for (int i = 1; i < Tot_jobs; i++)
            {
                for (int j = i + 1; j <= Tot_jobs; j++)
                {
                    batch[,] Tempseq = new batch[No_mc + 1, Tot_jobs + 1];
                    Array.Copy(Initialsequence, Tempseq, Initialsequence.Length);
                    batch tempstr = new batch(Tempseq[1, i].Family, Tempseq[1, i].Job);
                    Tempseq[1, i] = Tempseq[1, j];
                    Tempseq[1, j] = tempstr;

                    for (int k = 2; k <= No_mc; k++)
                    {
                        for (int l = 1; l <= Tot_jobs; l++)
                        {
                            Tempseq[k, l] = Tempseq[1, l];
                        }
                    }
                    NSJ.Add(Tempseq);                   

                }
            }            
        }

Answer 1

在CreateInitialSolution内，您正在重新定义变量Initialsequence。这隐藏了类级变量。所以改变这个：

batch[,] Initialsequence = new batch[No_mc + 1, Tot_jobs + 1];

对此：

Initialsequence = new batch[No_mc + 1, Tot_jobs + 1];

Answer 2

这是因为你实际上没有初始化你的Program类变量Initialsequence，而是你正在创建一个同名的本地方法变量，一旦你的方法执行完成就会超出范围，因此实际变量是仍null。如下面的代码块所示

 public static void CreateInitialSolution()
        {
            // CreateInitialSolution        
            batch[,] Initialsequence = new batch[No_mc + 1, Tot_jobs + 1];

SideNote：停止定义具有相同名称的变量，当您寻求帮助时会导致混淆和其他变量

从C＃中的另一个方法调用时，类变量重置为null

2 个答案: