Luhn test of credit card numbers: Difference between revisions

=={{header|Java Long type version}}==

<syntaxhighlight lang="java">public class Luhn {

public static void main(String[] args) {

System.out.println(luhnTest(49927398716L));

System.out.println(luhnTest(499273987163L));

System.out.println(luhnTest(1234567L));

System.out.println(luhnTest(0L));

}

public static boolean luhnTest(Long digits) {

int s1 = 0, s2 = 0;

//Use an alternator for separate odd/even processing

boolean alternator = true;

//Confine digit numbers to 8 - 19 per ISO

if (digits < 1e7 || digits >= 1e19) return false;

for ( int i = 0; digits > 0; ++i) {

Long oneDigit = digits % 10;

if (alternator) {

s1 += oneDigit.intValue();

} else {

oneDigit *= 2;

s2 += oneDigit > 9 ? oneDigit.intValue() - 9: oneDigit.intValue();

}

digits /= 10;

alternator = !alternator;

}

return (s1 + s2) % 10 == 0 ? true : false;

}

}</syntaxhighlight>

{{out}}

<pre>true

false

false

false</pre>