koobas.hobune.stream
C#: Arrays inside Arrays create a NullReferenceExeption?
Hello. I am currently trying to create a Minecarft-esc game in Unity, but I've run into this Problem: The compiler tells me, it ran into a NullReferenceExeption, when trying to aceess an Array that is stored within a class, of which I've created an Array. Let the code do the talking:
public class Chunk{
public int[ , , ] New_Chunk = new int[10, 3, 10];
}
[...]
public Chunk[ , , ] Created_Chunks = new Chunk[300, 300, 300];
[...]
Created_Chunks[x,y,z].New_Chunk[x1,y1,z1] = 2;
=> NullReferenceException: Object reference not set to an instance of an object
World_Creator.Start () (at Assets/World_Creator.cs:37)
Why is this happening? Ive tried it with making one instance of Chunk, without an array, which worked. Why is this happening? I need some Help :(
The error is almost clear: go to World_Creator.cs at line 37 you're trying to access the property of an object that is null (it's not still initialized). If you don't post the code of the function World_Creator.Start, as it is also clearly mentioned in the exception, we cannot be helpful.
Like @SkaredCreations said, this line:
public Chunk[ , , ] Created_Chunks = new Chunk[300, 300, 300];
just creates a ~100$$anonymous$$B large array with 27 million references which are all "null" since you did never create a single Chunk instance.
Each Chunk instance (if they are actually created with new Chunk()) would require, ignoring all overhead, at least 1200 bytes. So if you plan to initialize all elements in your Created_Chunks array you would require 27$$anonymous$$ * 1.2$$anonymous$$b == 32GB of memory. This is just ridiculous. You usually never need that many chunks at the same time. It's more common to use a dictionary to add / remove chunks on the fly.
Hello, you need to instantiate each object of class Chunk in order to access the members. Like Bunny pointed,
public Chunk[ , , ] Created_Chunks = new Chunk[300, 300, 300];
is merely creating some reference which are null. You need to create one Chunk instance for each of these reference. To do so
for(int i = 0 ;i< 300; ++i)
for(int j=0;j<300;++j)
for(int k=0;k<300;++k)
Created_Chunks[i,j,k] = new Chunk();
Of course, this code should not be used and you need to implement Lists or Dictionary.
Learn about those here : Scripting Tutorial
