C#对象引用未设置为对象的实例

Question

C#对象引用未设置为对象的实例

我得到的对象引用没有设置为第43行的对象实例,我无法弄清楚为什么,我搜索网络,似乎无法找到答案.我是C#的新手,一般都是编程,并且正在努力学习.如果有人可以帮助我,那就太好了

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace test
{
    public partial class Form1 : Form
    {
        [Serializable]
        public class ore 
        {
            public float Titan;
            public float Eperton;
        }

        ore b1 = null;
        ore b2 = null;

        public Form1()
        {
            InitializeComponent();

            ore b2 = new ore();
            ore b1 = new ore();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            float tempFloat;

            if (float.TryParse(textBox1.Text, out tempFloat))
            {
                b1.Titan = tempFloat; //line 43; where error happens
            }
            else
                MessageBox.Show("uh oh");
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            float tempFloat;
            if (float.TryParse(textBox1.Text, out tempFloat))
            {
                b2.Eperton = tempFloat;
            }
            else
                MessageBox.Show("uh oh");
        }

        private void button1_Click(object sender, EventArgs e)
        {
            List<ore> oreData = new List<ore>();
            oreData.Add(b1);
            oreData.Add(b2);

            FileStream fs = new FileStream("ore.dat", FileMode.Create);
            BinaryFormatter bf = new BinaryFormatter();
            bf.Serialize(fs, oreData);
            fs.Close();
        }
    }
}

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