CODEWITHSUNDEEP
c#exception
Leo
Leo

Reputation: 495

Exception Error in c#

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 FoolballLeague
{
    public partial class MainMenu : Form
    {
        FootballLeagueDatabase footballLeagueDatabase;
        Game game;
        Login login;

        public MainMenu()
        {
            InitializeComponent();
            changePanel(1);
        }

        public MainMenu(FootballLeagueDatabase footballLeagueDatabaseIn)
        {
            InitializeComponent();
            footballLeagueDatabase = footballLeagueDatabaseIn;
        }

        private void Form_Loaded(object sender, EventArgs e)
        {
        }



        private void gameButton_Click(object sender, EventArgs e)
        {
            int option = 0;
            changePanel(option);
        }
        private void scoreboardButton_Click(object sender, EventArgs e)
        {
            int option = 1;
            changePanel(option);
        }
        private void changePanel(int optionIn)
        {
            gamePanel.Hide();
            scoreboardPanel.Hide();

            string title = "Football League System";

            switch (optionIn)
            {
                case 0:
                    gamePanel.Show();
                    this.Text = title + " - Game Menu";
                    break;
                case 1:
                    scoreboardPanel.Show();
                    this.Text = title + " - Display Menu";
                    break;
            }
        }

        private void logoutButton_Click(object sender, EventArgs e)
        {
            login = new Login();
            login.Show();
            this.Hide();
        }

        private void addGameButton_Click(object sender, EventArgs e)
        {
            if ((homeTeamTxt.Text.Length) == 0)
                MessageBox.Show("You must enter a Home Team");
            else if (homeScoreUpDown.Value > 9 || homeScoreUpDown.Minimum < 0)
                MessageBox.Show("You must enter one digit between 0 and 9");
            else if ((awayTeamTxt.Text.Length) == 0)
                MessageBox.Show("You must enter a Away Team");
            else if (homeScoreUpDown.Value > 9 || homeScoreUpDown.Value < 0)
                MessageBox.Show("You must enter one digit between 0 to 9");
            else 
            {
                //checkGameInputFields();
                game = new Game(homeTeamTxt.Text, int.Parse(homeScoreUpDown.Value.ToString()), awayTeamTxt.Text, int.Parse(awayScoreUpDown.Value.ToString()));
                MessageBox.Show("Home Team -" + '\t' + homeTeamTxt.Text + '\t' + "and" + '\r' + "Away Team -" + '\t' + awayTeamTxt.Text + '\t' + "created");
                footballLeagueDatabase.AddGame(game);

                //clearCreateStudentInputFields();
            }
        }
        private void timer1_Tick(object sender, EventArgs e)
        {
            displayDateAndTime();
        }

        private void displayDateAndTime()
        {
            dateLabel.Text = DateTime.Today.ToLongDateString();
            timeLabel.Text = DateTime.Now.ToShortTimeString();
        }

        private void displayResultsButton_Click(object sender, EventArgs e)
        {
            Game game = new Game(homeTeamTxt.Text, int.Parse(homeScoreUpDown.Value.ToString()), awayTeamTxt.Text, int.Parse(awayScoreUpDown.Value.ToString()));

            gameResultsListView.Items.Clear();
            gameResultsListView.View = View.Details;

            ListViewItem row = new ListViewItem();
            row.SubItems.Add(game.HomeTeam.ToString());
            row.SubItems.Add(game.HomeScore.ToString());
            row.SubItems.Add(game.AwayTeam.ToString());
            row.SubItems.Add(game.AwayScore.ToString());

            gameResultsListView.Items.Add(row);
        }

        private void displayGamesButton_Click(object sender, EventArgs e)
        {
            Game game = new Game("Home", 2, "Away", 4);//homeTeamTxt.Text, int.Parse(homeScoreUpDown.Value.ToString()), awayTeamTxt.Text, int.Parse(awayScoreUpDown.Value.ToString()));

            modifyGamesListView.Items.Clear();
            modifyGamesListView.View = View.Details;

            ListViewItem row = new ListViewItem();
            row.SubItems.Add(game.HomeTeam.ToString());
            row.SubItems.Add(game.HomeScore.ToString());
            row.SubItems.Add(game.AwayTeam.ToString());
            row.SubItems.Add(game.AwayScore.ToString());

            modifyGamesListView.Items.Add(row);
        }

       }
    }

This is the whole code and I got same error like previous question.

Unhandled Exception has occurred in you application.If you click...............click Quit.the application will close immediately. Object reference not set to an instance of an object.

And the following details are in the error message.

************** Exception Text ************** System.NullReferenceException: Object reference not set to an instance of an object. at FoolballLeague.MainMenu.addGameButton_Click(Object sender, EventArgs e) in C:\Users\achini\Desktop\FootballLeague\FootballLeague\MainMenu.cs:line 91 at System.Windows.Forms.Control.OnClick(EventArgs e) at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ButtonBase.WndProc(Message& m) at System.Windows.Forms.Button.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

I need to add the games to using the addGameButton and the save those added games and display them in the list view (gameResultsListView). Now I can add a game and display in the list view.But when I pressed the button addGameButton I got the above error message.

If you can please give me a solution to this problem.

Upvotes: 1

Views: 359

Answers (5)

Blorgbeard
Blorgbeard

Reputation: 103535

You need to learn to read error messages and stack traces.

Look at this bit:

System.NullReferenceException: Object reference not set to an instance of an object. at FoolballLeague.MainMenu.addGameButton_Click(Object sender, EventArgs e) in C:\Users\achini\Desktop\FootballLeague\FootballLeague\MainMenu.cs:line 91

That tells you which line the error is at. It also tells you that it's a NullReferenceException, which means that something is null that shouldn't be.

Set a breakpoint, and step through the relevent code, examining what happens to the variables, and figure out how it ends up with that null value.

Upvotes: 4

Mark Byers
Mark Byers

Reputation: 839114

From the exception message I can see that you have a NullReferenceException in addGameButton_Click at line 91. This is line 91:

footballLeagueDatabase.AddGame(game);

So footballLeagueDatabase is null. Let's see the code where you assign to it:

public MainMenu()
{
    InitializeComponent();
    changePanel(1);
}

public MainMenu(FootballLeagueDatabase footballLeagueDatabaseIn)
{
    InitializeComponent();
    footballLeagueDatabase = footballLeagueDatabaseIn;
}

I'd guess either you called the wrong constructor, or you passed a null object into the constructor.

This is the whole code

No, it is not the whole code. You should have some other files in your project. The error is most likely in one of those files (the one that constructs this form).

Upvotes: 6

Rowland Shaw
Rowland Shaw

Reputation: 38128

It doesn't look like you initialise the footballLeagueDatabase anywhere

Upvotes: 2

driis
driis

Reputation: 164341

One of the references you are trying to access is null. It is on line 91 in your MainMenu.cs file. Set a breakpoint and have a look with the debugger, what is null?

I would guess that footballLeagueDatabase is null, you need to assign it an instance of type FootballLeagueDatabase.

Upvotes: 3

Francisco Soto
Francisco Soto

Reputation: 10392

Are you sure footballLeagueDatabase is getting initialized? I think the constructor where you initialize it is never getting called.

Upvotes: 2

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