Anonymous

public static boolean validateIsbn(String isbn){		// check length	if(isbn.length() != 10)	{		return false;	}		// validate characters	int num;	for(int i = 0; i < 10; i++)	{		num = Character.getNumericValue(isbn.charAt(i));		if(num < 0 || num > 9)		{			// if it is the last digit, we can allow an 'X'			if(i == 9 && isbn.charAt(i) == 'X')			{				continue;			}									return false;		}	}		// calculate checksum	int checkSum = 0;	for(int i = 0; i < 10; i++)	{		num = Character.getNumericValue(isbn.charAt(i));		if(i < 9)		{			checkSum += num * (10 - i);		}		else if(isbn.charAt(i) == 'X')		{			checkSum += 10;		}		else 		{			checkSum += num;		}			}		// validate checksum	if(checkSum % 11 != 0)	{		return false;	}	return true;}