private String bidForAuction() {
		if (user.isOnline()) {
			int auctionID = 0;
			double amount = 0.0;
			
			if (stringParts.length < 3) {
				return "Error: Please enter the bid- Command like this: " +
						"!bid <auction-id> <amount>";
			}
			try {
				auctionID = Integer.parseInt(stringParts[1]);
				amount = Double.parseDouble(stringParts[2]);
				amount = (double)(Math.round(amount*100))/100;
				
				if (amount <= 0 ) {
					return "Error: The amount has to be > 0!";
				}
			} catch (NumberFormatException e) {
				return "Error: Please enter the bid- Command like this: " +
						"!bid <auction-id> <amount>";
			} catch (ArrayIndexOutOfBoundsException e) {
				return "Error: Please enter the bid- Command like this: " +
						"!bid <auction-id> <amount>";
			}
			
			return userManagement.bidForAuction(user, auctionID, amount);
		}
		return "You have to log in first!";
	}