Does anyone know which slots of armorInventory[] on the EntityPlayer correspond to which armor items? I have googled it extensively and no one really lists it.

Also, if you look in ItemArmor, you will see that those are the opposite indexes of what you would use when creating armor:

/**
* Stores the armor type: 0 is helmet, 1 is plate, 2 is legs and 3 is boots
*/
public final int armorType;

Confusing that they don't match, eh? But the indexes you want for your question are the ones diesieben07 pointed out.

Thank you. I heard that the Chestplate was 3, but that didn't make sense so I decided to ask.

Thank you. I heard that the Chestplate was 3, but that didn't make sense so I decided to ask.

It is 3 if you use player.getEquipmentInSlot(i), as slot 0 is the held item and 1-4 are the armor slots, with the same indexes as diesieben07 mentioned but all incremented by 1. You don't have to shift the index if you use player.getCurrentArmor(i).