Question

我正在做一个C＃课程，我不得不制作太空入侵者风格的游戏。我不确定如何，但我一直遇到这个错误

System.NullReferenceException

对象引用未设置为对象的实例

这是我目前的代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.Serialization;

namespace Space_Invaders_Clone
{
    public partial class Form1 : Form
    {

        int BulletsCreated = 0;
        PictureBox[] bullets = new PictureBox[999];

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            //MessageBox.Show(e.KeyValue.ToString());
            if (e.KeyValue == 37 && Turret.Left > 12)
            {
                Turret.Left = Turret.Left - 5;
            }

            if (e.KeyValue == 39 && Turret.Left < 593)
            {
                Turret.Left = Turret.Left + 5;
            }

            if (e.KeyValue == 32)
            {
                bullets[BulletsCreated] = new PictureBox();
                bullets[BulletsCreated].Width = 2;
                bullets[BulletsCreated].Height = 24;
                bullets[BulletsCreated].BackColor = Color.Cyan;
                bullets[BulletsCreated].Top = Turret.Top - 26;
                bullets[BulletsCreated].Left = Turret.Left + Turret.Width / 2;
                bullets[BulletsCreated].Enabled = true;
                bullets[BulletsCreated].Visible = true;
                this.Controls.Add(bullets[BulletsCreated]); //add to controls
                BulletsCreated++;
            }
        }



                    private void BulletTimer_Tick(object sender, EventArgs e)
        {

            bullets[0].Top = bullets[0].Top - 10;
        }



    }


}

此行发生错误：

bullets[0].Top = bullets[0].Top - 10;

我做错了什么？

Answer 1

在处理keyvalue 32之前调用方法BulletTimer_Tick。因此，您尝试读取并更新不存在的地址0处的值。

我在代码中做错了什么？ NullReferenceException错误

1 个答案: