Yazılım | Programlama System.NullReferenceException: 'Nesne başvurusu bir nesnenin örneğine ayarlanmadı.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SQLite;
using Microsoft.Data.Sqlite;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace projedeneme
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

SQLiteConnection con;
SQLiteDataAdapter da;
SQLiteCommand cmd;
DataSet ds;
SQLiteDataReader dr;

**** GetList()
{
NewMethod();
da = new SQLiteDataAdapter("Select *From user", con);
ds = new DataSet();
con.Open();
da.Fill(ds, "user");

con.Close();
}

private **** NewMethod()
{
con = new SQLiteConnection("Data Source=mustafa.db3;Version=3;");
}

public Form1(IContainer components, PictureBox pictureBox1, TextBox textBox1, TextBox textBox2, Label label1, Label label2, Button button1, SQLiteConnection con, SQLiteDataAdapter da, SQLiteCommand cmd, DataSet ds, SQLiteDataReader dr)
{
this.components = components;
this.pictureBox1 = pictureBox1;
this.textBox1 = textBox1;
this.textBox2 = textBox2;
this.label1 = label1;
this.label2 = label2;
this.button1 = button1;
this.con = con;
this.da = da;
this.cmd = cmd;
this.ds = ds;
this.dr = dr;
}




private **** button1_Click(object sender, EventArgs e)
{

cmd = new SQLiteCommand();
NewMethod1();
cmd.Connection = con;
con = new SQLiteConnection("Data Source=mustafa.db3;Version=3;");
cmd.CommandText = "SELECT * FROM user where username='" + textBox1.Text + "' AND password='" + textBox2.Text + "'";
dr = cmd.ExecuteReader();
if (dr.Read())
{
Form2 f2 = new Form2();
f2.Show();
}
else
{
MessageBox.Show("Kullanıcı adı ya da şifre yanlış");
}

con.Close();






GetList();





}

private **** NewMethod1()
{
con.Open();
}
}
}

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