Question

当我制作seats[] seatArray并尝试运行它时，我收到错误

NullReferenceException未处理。你调用的对象是空的。

我认为最后是我的printinfo功能。

namespace WindowsFormsApplication2
{      
    public partial class Form1 : Form
    {
       Seats s = new Seats();
        //Seats[] seatArray = new Seats[14]; //HEREEE
        public Form1()
        {

            InitializeComponent();
            listBox2.Items.Add("ROW#   A   B   C   D   E   F");
            listBox2.Items.Add("  1    " + s.PrintInfo);
           // listBox2.Items.Add( seatArray[0].PrintInfo); //HEREEE

            listBox1.Items.Add("Seats Filled:");
            listBox1.Items.Add("Windows Available:");
            listBox1.Items.Add("Regular Meals:");
            listBox1.Items.Add("LowCal Meals:");
            listBox1.Items.Add("Veget Meals:");

        }

        private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            string test = listBox2.SelectedItem.ToString(); /
            //string[] div = Regex.Split(test, "     ");
            //textBox2.Text = div[0];
            textBox2.Text = test; //     
        }
    }

    public class Seats // 
    {
        public char A;
        public char B;
        public char C;
        public char D;
        public char E;
        public char F;

        public Seats()
        {
            A = '.';
            B = '.';
            C = '.';
            D = '.';
            E = '.';
            F = '.';
        }

        public char Aa
        {
            set { A = value; }
            get { return A; }
        }
        public char Bb
        {
            set { A = value; }
            get { return A; }
        }
        public char Cc
        {
            set { C = value; }
            get { return C; }
        }
        public char Dd
        {
            set { D = value; }
            get { return D; }
        }
        public char Ee
        {
            set { E = value; }
            get { return E; }
        }
        public char Ff
        {
            set { F = value; }
            get { return F; }
        }


        public string PrintInfo // 
        {
            get { return this.A + "    " + this.B + "    " + this.C + "    " + this.D + "    " + this.E + "    " + this.F; }


        }
    }
}

Answer 1

创建数组时，它将填充给定类型的默认值。对于参考类型，默认值为null。您需要先将数据添加到数组中，然后才能使用它们：

Seats[] seatArray = new Seats[14]; 
seatArray[0] = new Seat();   // or something like this
public Form1()
{

    InitializeComponent();
    listBox2.Items.Add("ROW#   A   B   C   D   E   F");
    listBox2.Items.Add("  1    " + s.PrintInfo);
    listBox2.Items.Add( seatArray[0].PrintInfo); //HEREEE

如果您想创建一个包含14个未初始化席位的阵列，您可以使用：

Seats[] seatArray = Enumerable.Repeat(new Seat(),14).ToArray();

从类对象创建一个数组

1 个答案: