Verhoeff algorithm: Difference between revisions
→{{header|Java}}
Line 483:
<syntaxhighlight>
import java.util.Arrays;
import java.util.List;
public class VerhoeffAlgorithm {
public static void main(String[] args) {
initialise();
List<List<Object>> tests = List.of(
List.of( "236", false, true ), List.of( "12345", false, true ), List.of( "123456789012", false, false ) );
for ( List<Object> test : tests ) {
Object object = verhoeffChecksum((String) test.get(0), false, (boolean) test.get(2));
System.out.println("The check digit for " + test.get(0) + " is " + object + "\n");
for ( String number : List.of( test.get(0) + object.toString(), test.get(0) + "9" ) ) {
object = verhoeffChecksum(number, true, (boolean) test.get(2));
String result = (boolean) object ? "correct" : "incorrect";
System.out.println("The validation for " + number + " is " + result + ".\n");
}
}
}
private static Object verhoeffChecksum(String number, boolean doValidation, boolean doDisplay) {
if ( doDisplay ) {
String calculationType = doValidation ? "Validation" : "Check digit";
System.out.println(calculationType + " calculations for " + number + "\n");
System.out.println(" i ni p[i,ni] c");
System.out.println("------------------");
}
if ( ! doValidation ) {
number += "0";
}
int c = 0;
final int le = number.length() - 1;
for ( int i = le; i >= 0; i-- ) {
final int ni = number.charAt(i) - '0';
final int pi = permutationTable.get((le - i) % 8).get(ni);
c = multiplicationTable.get(c).get(pi);
if ( doDisplay ) {
System.out.println(String.format("%2d %d %d %d\n", le - i, ni, pi, c));
}
}
if ( doDisplay && ! doValidation ) {
System.out.println("inv[" + c + "] = " + inverse.get(c) + "\n");
}
return doValidation ? c == 0 : inverse.get(c);
}
private static void initialise() {
multiplicationTable = List.of(
List.of( 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ),
List.of( 1, 2, 3, 4, 0, 6, 7, 8, 9, 5 ),
List.of( 2, 3, 4, 0, 1, 7, 8, 9, 5, 6 ),
List.of( 3, 4, 0, 1, 2, 8, 9, 5, 6, 7 ),
List.of( 4, 0, 1, 2, 3, 9, 5, 6, 7, 8 ),
List.of( 5, 9, 8, 7, 6, 0, 4, 3, 2, 1 ),
List.of( 6, 5, 9, 8, 7, 1, 0, 4, 3, 2 ),
List.of( 7, 6, 5, 9, 8, 2, 1, 0, 4, 3 ),
List.of( 8, 7, 6, 5, 9, 3, 2, 1, 0, 4 ),
List.of( 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 )
);
inverse = Arrays.asList( 0, 4, 3, 2, 1, 5, 6, 7, 8, 9 );
permutationTable = List.of(
List.of( 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ),
List.of( 1, 5, 7, 6, 2, 8, 3, 0, 9, 4 ),
List.of( 5, 8, 0, 3, 7, 9, 6, 1, 4, 2 ),
List.of( 8, 9, 1, 6, 0, 4, 3, 5, 2, 7 ),
List.of( 9, 4, 5, 3, 1, 2, 6, 8, 7, 0 ),
List.of( 4, 2, 8, 6, 5, 7, 3, 9, 0, 1 ),
List.of( 2, 7, 9, 3, 8, 0, 6, 4, 1, 5 ),
List.of( 7, 0, 4, 6, 9, 1, 3, 2, 5, 8 )
);
}
private static List<List<Integer>> multiplicationTable;
private static List<Integer> inverse;
private static List<List<Integer>> permutationTable;
}
</syntaxhighlight>
{{ out }}
<pre>
The same as the Wren example.
</pre>
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