Thread: Null Exception

Hello could someone help explain this error to me

Code:

java.lang.NullPointerException
     at com.rs.game.player.content.Trade.endSession(Trade.java:380)

Code:

	public void endSession() {
		trader.getInterfaceManager().closeScreenInterface();
		trader.getInterfaceManager().closeInventoryInterface();
		partner.getInterfaceManager().closeScreenInterface();
		partner.getInterfaceManager().closeInventoryInterface();
		traderItemsOffered = null;
		partnerItemsOffered = null;
		trader.setTradeSession(null);
		partner.setTradePartner(null);
		partner.setTradeSession(null);
		trader.setTradePartner(null);
		trader.setNextFaceEntity(null);
		partner.setNextFaceEntity(null);
	}

I understand that it is trying to process something that is nulled but how would I fix it? Thanks

Update: Found what was causing the error in my player.java I have this under closeinterfaces()

Code:

	public void closeInterfaces() {
		if (getTradeSession() != null && getTradeSession().getPartner() != null)
			getTradeSession().tradeFailed();

How come this is throwing me this error?

Update2: Figured it out .. I put the code in the wrong place. Ill post the code here in case someone else has the same issue.

Code:

	public void closeInterfaces() {
		if (interfaceManager.containsScreenInter())
			interfaceManager.closeScreenInterface();
		if (interfaceManager.containsInventoryInter())
			interfaceManager.closeInventoryInterface();
		dialogueManager.finishDialogue();
		if (closeInterfacesEvent != null) {
			closeInterfacesEvent.run();
			closeInterfacesEvent = null;
		}
		if (getTradeSession() != null && getTradeSession().getPartner() != null)
			getTradeSession().tradeFailed();
	}

Credits go to grundyboy34