/**
* An ISBN Utility
* @author Julius Schorzman
* (C) 2006 -- Provided under GPL
*/
public class ISBNUtil {
/**
* Checks if the passed string is a valid ISBN number.
* @param isbn The ISBN String
* @return true if it is a valid isbn; false in all other cases.
*/
public static boolean isISBN
(String isbn
) {
try {
if (isbn.length() != 10) {
return false;
}
int weight = 10;
int rollingSum = 0;
for ( int i = 0 ; i < 9 ; i++ ) {
int isbnDigit
= Character.
digit(isbn.
charAt(i
),
10); rollingSum += isbnDigit * weight--;
}
int mod = rollingSum % 11;
mod = 11 - mod;
if ( mod == 11 ) mod = 0;
char checkSum = isbn.charAt(9);
if (Character.
toLowerCase(checkSum
) == 'x') { if ( mod == 10 ) return true;
} else {
if (Character.
digit(checkSum,
10) == mod
) return true; }
return false;
return false;
}
}
public static void main
(String[] args
) { System.
out.
println("true: "+ISBNUtil.
isISBN("031234161X")); System.
out.
println("true: "+ISBNUtil.
isISBN("0525949488")); System.
out.
println("true: "+ISBNUtil.
isISBN("076360013X")); System.
out.
println("true: "+ISBNUtil.
isISBN("0671027360")); System.
out.
println("true: "+ISBNUtil.
isISBN("0803612079")); System.
out.
println("true: "+ISBNUtil.
isISBN("0307263118")); System.
out.
println("true: "+ISBNUtil.
isISBN("0684856093")); System.
out.
println("true: "+ISBNUtil.
isISBN("0767916565")); System.
out.
println("true: "+ISBNUtil.
isISBN("0071392319")); System.
out.
println("true: "+ISBNUtil.
isISBN("1400032806")); System.
out.
println("true: "+ISBNUtil.
isISBN("0765305240"));
System.
out.
println("false: "+ISBNUtil.
isISBN("0312341613")); System.
out.
println("false: "+ISBNUtil.
isISBN("052594948X")); System.
out.
println("false: "+ISBNUtil.
isISBN("0763600138")); System.
out.
println("false: "+ISBNUtil.
isISBN("0671027364")); System.
out.
println("false: "+ISBNUtil.
isISBN("080361207X")); System.
out.
println("false: "+ISBNUtil.
isISBN("0307263110")); System.
out.
println("false: "+ISBNUtil.
isISBN("0684856092")); System.
out.
println("false: "+ISBNUtil.
isISBN("0767916567")); System.
out.
println("false: "+ISBNUtil.
isISBN("0071392318")); System.
out.
println("false: "+ISBNUtil.
isISBN("1400032801")); System.
out.
println("false: "+ISBNUtil.
isISBN("0765305241")); }
}
//java/8307