NullReferenceException

Terreliorz · May 18, 2016, 2:21pm

Hi, I am in the process of developing a new board game in unity. This is my first game and am quite new to scripting in C#. I am trying to write some code that shall populate a 2D array class of initial game board data but am receiving the following error:

NullReferenceException: Object reference not set to an instance of an object
GameController.Start () (at Assets/Scripts/GameController.cs:100)

Any help would be appreciated. Thanks.

using UnityEngine;
using System.Collections;

[System.Serializable]
public class GameBoardData {

    private float xCoord;
    private float zCoord;
    private int[,] visorPositons = new int[4,3];
    private bool player;
    private bool[] gridSpace = new bool[4];

    public void SetCoords( float x, float z )
    {
        xCoord = x;
        zCoord = z;
    }
    public float[] GetCoords()
    {
        float[] xy = { xCoord, zCoord };
        return xy;
    }
    public void SetVisorPositions( int[,] vp )
    {
        visorPositons = vp;
    }
    public int[,] GetVisorPositions()
    {
        int[,] vp = visorPositons;
        return vp;
    }
    public void SetPlayer( bool pl )
    {
        player = pl;
    }
    public bool GetPlayer()
    {
        bool pl = player;
        return player;
    }
    public void SetGridSpace( bool[] gs)
    {
        gridSpace = gs;
    }
    public bool[] GetGridSpace()
    {
        bool[] gs = gridSpace;
        return gs;
    }

}

public class GameController : MonoBehaviour {

    private float[,,] coordData = new float[8, 11, 2]
        { { {0.0f,  2.88675f},  {5.0f,  0.0f},     {10.0f, 2.88675f},  {15.0f, 0.0f},     {20.0f, 2.88675f},  {25.0f, 0.0f},
            {30.0f, 2.88675f},  {35.0f, 0.0f},     {40.0f, 2.88675f},  {45.0f, 0.0f},     {50.0f, 2.88675f} },
          { {0.0f,  8.66025f},  {5.0f,  11.547f},  {10.0f, 8.66025f},  {15.0f, 11.547f},  {20.0f, 8.66025f},  {25.0f, 11.547f},
            {30.0f, 8.66025f},  {35.0f, 11.547f},  {40.0f, 8.66025f},  {45.0f, 11.547f},  {50.0f, 8.66025f} },
          { {0.0f,  20.20725f}, {5.0f,  17.3205f}, {10.0f, 20.20725f}, {15.0f, 17.3205f}, {20.0f, 20.20725f}, {25.0f, 17.3205f},
            {30.0f, 20.20725f}, {35.0f, 17.3205f}, {40.0f, 20.20725f}, {45.0f, 17.3205f}, {50.0f, 20.20725f} },
          { {0.0f,  25.98075f}, {5.0f,  28.8675f}, {10.0f, 25.98075f}, {15.0f, 28.8675f}, {20.0f, 25.98075f}, {25.0f, 28.8675f},
            {30.0f, 25.98075f}, {35.0f, 28.8675f}, {40.0f, 25.98075f}, {45.0f, 28.8675f}, {50.0f, 25.98075f} },
          { {0.0f,  37.52775f}, {5.0f,  34.641f},  {10.0f, 37.52775f}, {15.0f, 34.641f},  {20.0f, 37.52775f}, {25.0f, 34.641f},
            {30.0f, 37.52775f}, {35.0f, 34.641f},  {40.0f, 37.52775f}, {45.0f, 34.641f},  {50.0f, 37.52775f} },
          { {0.0f,  43.30125f}, {5.0f,  46.188f},  {10.0f, 43.30125f}, {15.0f, 46.188f},  {20.0f, 43.30125f}, {25.0f, 46.188f},
            {30.0f, 43.30125f}, {35.0f, 46.188f},  {40.0f, 43.30125f}, {45.0f, 46.188f},  {50.0f, 43.30125f} },
          { {0.0f,  54.84825f}, {5.0f,  51.9615f}, {10.0f, 54.84825f}, {15.0f, 51.9615f}, {20.0f, 54.84825f}, {25.0f, 51.9615f},
            {30.0f, 54.84825f}, {35.0f, 51.9615f}, {40.0f, 54.84825f}, {45.0f, 51.9615f}, {50.0f, 54.84825f} },
          { {0.0f,  60.62175f}, {5.0f,  63.5085f}, {10.0f, 60.62175f}, {15.0f, 63.5085f}, {20.0f, 60.62175f}, {25.0f, 63.5085f},
            {30.0f, 60.62175f}, {35.0f, 63.5085f}, {40.0f, 60.62175f}, {45.0f, 63.5085f}, {50.0f, 60.62175f} } };

    private bool[,,] gridSpaceData = new bool[8, 11, 4]
        { { { true, false, false, true }, { false, false, true, true }, { true, false, true, true }, { false, false, true, true }, { true, false, true, true }, { false, false, true, true },
            { true, false, true, true },  { false, false, true, true }, { true, false, true, true }, { false, false, true, true }, { true, false, true, false } },
          { { false, true, false, true }, { true, false, true, true },  { false, true, true, true }, { true, false, true, true },  { false, true, true, true }, { true, false, true, true },
            { false, true, true, true },  { true, false, true, true },  { false, true, true, true }, { true, false, true, true },  { false, true, true, false } },
          { { true, false, false, true }, { false, true, true, true },  { true, false, true, true }, { false, true, true, true },  { true, false, true, true }, { false, true, true, true },
            { true, false, true, true },  { false, true, true, true },  { true, false, true, true }, { false, true, true, true },  { true, false, true, false } },
          { { false, true, false, true }, { true, false, true, true },  { false, true, true, true }, { true, false, true, true },  { false, true, true, true }, { true, false, true, true },
            { false, true, true, true },  { true, false, true, true },  { false, true, true, true }, { true, false, true, true },  { false, true, true, false } },
          { { true, false, false, true }, { false, true, true, true },  { true, false, true, true }, { false, true, true, true },  { true, false, true, true }, { false, true, true, true },
            { true, false, true, true },  { false, true, true, true },  { true, false, true, true }, { false, true, true, true },  { true, false, true, false } },
          { { false, true, false, true }, { true, false, true, true },  { false, true, true, true }, { true, false, true, true },  { false, true, true, true }, { true, false, true, true },
            { false, true, true, true },  { true, false, true, true },  { false, true, true, true }, { true, false, true, true },  { false, true, true, false } },
          { { true, false, false, true }, { false, true, true, true },  { true, false, true, true }, { false, true, true, true },  { true, false, true, true }, { false, true, true, true },
            { true, false, true, true },  { false, true, true, true },  { true, false, true, true }, { false, true, true, true },  { true, false, true, false } },
          { { false, true, false, true }, { false, false, true, true }, { false, true, true, true }, { false, false, true, true }, { false, true, true, true }, { false, false, true, true },
            { false, true, true, true },  { false, false, true, true }, { false, true, true, true }, { false, false, true, true }, { false, true, true, false } } };

    public GameBoardData[,] GBD = new GameBoardData[8, 11];
    // Use this for initialization
    void Start () {

        for ( int i = 0; i < 8; i++)
            for( int j = 0; j < 11; j++ )
            {   
                GBD[i, j] = new GameBoardData();

                GBD[i, j].SetCoords(coordData[i, j, 0], coordData[i, j, 1]); // error
                bool[] gs = { gridSpaceData[i, j, 0], gridSpaceData[i, j, 1], gridSpaceData[i, j, 2], gridSpaceData[i, j, 3] };
                GBD[i, j].SetGridSpace(gs);
            }

    }

    // Update is called once per frame
    void Update () {
        if (Input.GetKeyDown(KeyCode.E))
            Application.Quit();
    }
}

KelsoMRK · May 18, 2016, 2:25pm

Lots of posts all over the place addressing this.

Null means that something doesn’t exist. You get a NullReferenceException when you attempt to access a member of something that doesn’t exist. You’re doing that on line 100 of your GameController class.

Terreliorz · May 19, 2016, 3:19pm

I uncovered the cause of the problem is that unity doesn’t seem to be able to serialize a 2D class array and therefore not recognize it.
Using this array would be convenient for me. Any way around this or is there some better method that I might employ.
Thanks.

public GameBoardData[,] GBD = new GameBoardData[8, 11];
    // Use this for initialization
    void Start () {

        for ( int i = 0; i < 8; i++)
            for( int j = 0; j < 11; j++ )
            {          
                GBD[i, j].SetCoords(coordData[i, j, 0], coordData[i, j, 1]); // error
                bool[] gs = { gridSpaceData[i, j, 0], gridSpaceData[i, j, 1], gridSpaceData[i, j, 2], gridSpaceData[i, j, 3] };
                GBD[i, j].SetGridSpace(gs);
            }

Lanre · May 28, 2016, 2:37pm

Terreliorz:

I uncovered the cause of the problem is that unity doesn’t seem to be able to serialize a 2D class array and therefore not recognize it.
Using this array would be convenient for me. Any way around this or is there some better method that I might employ.
Thanks.
public GameBoardData[,] GBD = new GameBoardData[8, 11];
    // Use this for initialization
    void Start () {

        for ( int i = 0; i < 8; i++)
            for( int j = 0; j < 11; j++ )
            {         
                GBD[i, j].SetCoords(coordData[i, j, 0], coordData[i, j, 1]); // error
                bool[] gs = { gridSpaceData[i, j, 0], gridSpaceData[i, j, 1], gridSpaceData[i, j, 2], gridSpaceData[i, j, 3] };
                GBD[i, j].SetGridSpace(gs);
            }

Unity should be able to serialize a data container. Try this:

[System.Serializable]
public class GameBoardData {
...
}

Terreliorz · May 28, 2016, 7:58pm

Yes, I have since tried that as reflected in my updated code snippet up top. But it still fails to recognise the class in voidStart(){…

Eudaimonium · May 29, 2016, 9:07am

I was going over your code 10th time now thinking “This SHOULD be working”…

Then it hit me. I also did the same mistake like a dozen times per project and I just never learn.

for ( int i = 0; i < 8; i++)
            for( int j = 0; j < 11; j++ )
            {       
               // This guddam thing:
              GBD[i,j] = new GBD();

                GBD[i, j].SetCoords(coordData[i, j, 0], coordData[i, j, 1]); // no more error

New array allocation does not create individual instances in the array

Terreliorz · May 29, 2016, 1:24pm

Thanks for the insight, but still dosen’t work…

Error CS0246 The type or namespace name ‘GBD’ could not be found (are you missing a using directive or an assembly reference?)

Eudaimonium · May 29, 2016, 1:26pm

Arrgh, what I meant was,

new GameBoardData();

Apologies!

Terreliorz · May 29, 2016, 1:53pm

Thanks, but still getting NullReferenceException error…

Eudaimonium · May 29, 2016, 2:01pm

Where, on which line? Cannot be same one, I think we sorted that. Can we see your code with all the changes again?

Terreliorz · May 29, 2016, 2:21pm

My oversight . I had some irrelevant test code in there. Took it out and works just fine now.
Thanks a million!

Eudaimonium · May 29, 2016, 2:30pm

No problems.

Also, can’t help but note there was some value hardcoding in your Game Controller class up there… maybe you want to consider generating them with an algorithm?

Terreliorz · May 29, 2016, 3:53pm

To be honest game development isn’t my line of expertise. I don’t have a significant knowledge of programming or mathematics so the writing of algorithms was going to be quite a challenge for me.
Ideally what I’m looking for is someone that could take over this project for me so I could concentrate on other things.

I found a university lecturer that proposed he and his students could take it over and develop with unreal engine using a node based system for the a.i. I feel however that unity would be a better development environment for this game as could be achieved with C#.

If interested perhaps I could share what I’ve done so for with you and if you like it I could hand the project over to you and we could go 50/50 on the profits.

Thanks for all the help.

Eudaimonium · May 29, 2016, 3:57pm

I am not really interested (since I have several ongoing projects of my own), but there is a subforum for something like that.

Best of luck!

BTW yeah Unity will probably get you some prototype results and demo state much faster than Unreal Engine, under assumption that you worked with neither before. UE can be kind of tough at times.

Terreliorz · May 29, 2016, 4:30pm

OK thats fine. I hope you do well with your projects. Any suggestions for developing good algorithms? Thanks again.

Eudaimonium · May 29, 2016, 4:33pm

Yeah, keep working on your projects No other advice than that.

Whenever you get stuck, google it. If there are no results, there has to be another way, different approach.

Same as with anything else, the more you work with it, the better you are at it. Happy coding