I have a program in which a user buys an item at a store. I have the user input the itemName, quantity, unitPrice, and whether it is taxable or not in a String which is tokenized into four parts, delimited by the "|" character. Example: itemName|quantity|unitPrice|N The N or n in the fourth token tells whether the purchase is taxable. How can I use Java to reject the input and display an error message to the user if the fourth token is not input as a "n" or a "N"? Any help is greatly appreciated!