尝试使用我的第一个用户定义类型时发生NullReferenceException

Question

What I'm trying to do is define my own type that contains 2 int s to use in a 2-dimensional array. The application for this is using the array indexes as x,y coordinates for objects in 2-d space to be displayed. So object with data stored at array[13,5] would be displayed at x=13,y=5, and the properties of that object could be retrieved with array[13,5].property1 , for example. The type I've defined is extremely simple:

chunkBlocks.cs:
public class chunkBlocks {
    public int blockType;
    public int isLoaded;
}

then, I initialize the array:

chunkBlocks[,] _bData = new chunkBlocks[17, 17];

This all compiles/runs without error. The NRE is thrown when I try to assign a value to one of the properties of the type. For debugging, I have the code written as:

_bData[i, n].blockType = 5;

and the NRE is thrown specifically on the .blockType portion. I've tried changing the type to initialize with 0 values for both int s to no avail:

public class chunkBlocks {
    public int blockType = 0;
    public int isLoaded = 0;
}

I've Googled around and searched SO, and I've not been able to turn up anything. I'm sure it's a relatively simple matter, but I'm not experienced enough to be able to pinpoint it.

Thanks!

Answer 1

You need to initialize every instance of the array:

_bData[i, n] = new chunkBlocks();

Now assign the value to it:

_bData[i, n].blockType = 5;

You will have to initialize every instance, you just have declared them in the array.

Answer 2

I think you should do this:

for(int i = 0;i<17;i++)
{
    for (int j = 0; j < 17; j++)
    {
         _bData[i, j] = new chunkBlocks ();
    }
}