How to make a custom mob such that only one can naturally spawn in the world at a time?

[NarwhelZhu]

I'm trying to make a mob that will only naturally spawn once in a world at a time until it's either killed or it despawns, but for some reason my code isn't working and I'm not sure why.

 

Here is my code, can someone tell me what I'm doing wrong? There are no errors when I load up the world, but it seems that the world.getLoadedEntityList().contains(this) is always returning false, even when one entity already exists, so more than one can spawn in the world. That tells me I'm using the method wrong, but I'm not sure what else to use or what I'm doing wrong with it.

 

public class EntityRumia extends EntityMob {

	public EntityRumia(World worldIn) {
		super(worldIn);
		this.setSize(0.6F, 1.8F);
	}
	
	@Override
	public boolean getCanSpawnHere() {
		return !world.getLoadedEntityList().contains(this) && super.getCanSpawnHere();
	}
}

 

[Animefan8888]

7 minutes ago, NarwhelZhu said:

world.getLoadedEntityList().contains(this)

Unless you override the equals method checking if a list contains an entity whom we will call instance a when instance b is already there will always return false. You need to iterate through the list of entities and check if one is an instance of your entities class. And if it is say it cant spawn. 

[NarwhelZhu]

This seems to work, thank you very much.