What is a NumberFormatException and how can I fix it?

Question

Error Message:
Exception in thread \"main\" java.lang.NumberFormatException: For input string: \"Ace of Clubs\"
    at java.lang.NumberFormatException.forInputString         


        

Answer 1

A NumberFormatException means that Integer.parseInt() couldn't translate the string into a number.

I would suggest one of two options:

1. Encapsulate cards as a name(string)/value(int) combo. Use the value to do comparisons, and the name to present info to the user. Cards[] then becomes a list of cards, not strings.

2. Parse the strings yourself. Which may be easier, since you've already done it with the if(cards[index].startsWith("Ace")) { value = 1; } bits. You can move those into a function called CardToInt() (or whatever), and use that function instead of Integer.parseInt().

Answer 2

Looks like cards[] is String array and you are trying to convert Ace of Clubs to Integer.

int first_value = Integer.parseInt(cards[index]);

Answer 3

java.lang.NumberFormatException 

occurs when you are trying to parse some input which not a Number string.

In your case your trying to parse a string (which not has number )as Integer. As its not possible NumberFormatException exception occured.

int first_value = Integer.parseInt(cards[index]);//cards[index] value should be //number string "123" not "abc"