koobas.hobune.stream
Reflection NullReferenceException: Object reference not set to an instance of an object
Hi,
I've been trying to figure out how to load a level by referencing an int that's a variable in a different object's script, but I'm doing something wrong.
I'm passing in the name of the int through the inspector and trying to use reflection:
private GameObject manager;
public void ClickAsync(string levelName)
{
manager = GameObject.Find("GameManager");
int levelValue = (int)manager.GetType().GetField(levelName).GetValue(manager);
loadingImage.SetActive(true);
StartCoroutine(LoadLevelWithBar(levelValue));
}
I'm getting this error:
NullReferenceException: Object reference not set to an instance of an object Script_ClickToLoadAsync.ClickAsync (System.String levelName) (at Assets/scripts/Script_ClickToLoadAsync.cs:19)
Line 19 is this line:
int levelValue = (int)manager.GetType().GetField(levelName).GetValue(manager);
Could someone please explain to me what I'm doing wrong and how to solve this?
Thank you in advance for your assistance.
Try to split that sausage up and identify the null reference. Try something like:
Type type = manager.GetType();
FieldInfo field = type.GetField(levelName);
object value = field.GetValue(manager);
int levelValue = (int)value;
Of course, make sure manager and levelName are not null, and if not, you'll easily identify which Get... fails to find what you're looking for.
I've done that and I can see that field is turning up Null, with the same error as above. I don't understand how to fix it though. I've tested levelName and it matches the variable name in the manager GameObject's script (Script_Game$$anonymous$$anager).
Is your field public? If not, try specifying the binding flags https://msdn.microsoft.com/en-us/library/4ek9c21e(v=vs.110).aspx
I think so, as the class and int are both public, as per the example in the reference you linked.
public class Script_Game$$anonymous$$anager : $$anonymous$$onoBehaviour
{
public int lvlGame = 3;
}
I've tried specifying all possible binding flags and it hasn't helped.
I figured out what I was doing wrong.
int levelValue = (int)manager.GetType().GetField(levelName).GetValue(manager);
Should have been:
int levelValue = (int)manager.GetComponent<Script_GameManager>().GetType().GetField(levelName).GetValue(manager.GetComponent<Script_GameManager>());
This is why my field was turning up Null.
I know this is an old post but to help clarify GetValue() needs to be passed an instance of the type for which you get field info in reflection.
