regular expressions in Java

Question

i attempted to port the code in this answer to Java: PHP VIN number validation code

i understand that String.matches in Java is a bit temperamental and i'm very unfamiliar with regular expressions. here is the code:

public boolean validateVIN(String vin) {
    vin = vin.toLowerCase();

    if(!vin.matches("/^[^\\Wioq]{17}$/")) { //the offending code, always fails
        Log.e("vininfo", "did not pass regex");
        return false;
    }

    int[] weights = { 8, 7, 6, 5, 4, 3, 2, 10, 0, 9, 8, 7, 6, 5, 4, 3, 2 };

    //array positions coorespond to the 26 letters of the alphabet
    int[] transliterations = { 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 0, 7, 0, 9, 2, 3, 4, 5, 6, 7, 8, 9 };

    int sum = 0;
    String checkdigit = ".";

    for(int i=0; i < vin.length(); i++) {
        //add transliterations * weight of their positions to get the sum
        int temp = 0;
        temp = vin.charAt(i);
        if(temp < 58) {
            sum += (temp-48)*weights[i];
            Log.e("vinsum.num", String.valueOf(sum));
        } else {
            sum += transliterations[temp-97]*weights[i];
            Log.e("vinsum.chr", String.valueOf(sum));
        }
    }

    if(checkdigit.equals("10")) {
        checkdigit = "x";
    } else {
        //find checkdidgit by taking the mod of the sum
        checkdigit = String.valueOf(sum % 11);
    }

    Log.i("vininfo", "checkdigit: "+checkdigit+" ... VIN[8]: "+vin.substring(8,9));
    return (checkdigit.equals(vin.substring(8, 9)));
}

anyone familiar with a proper way to use this regex in Java?

If removing the slashes don't work, print out vin before you exit. It looks like vin should all be lower case. If all else fails, use a debugger. — , Feb 16 '11 at 20:19

score 6 · Accepted Answer · answered Feb 16 '11 at 20:11

6

Remove the slashes from the regex. In other words:

if(!vin.matches("^[^\\Wioq]{17}$")) {

answered Feb 16 '11 at 20:11

Thomas

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19

@moonlightcheese - Just a fyi if you don't convert the vin to lower case (as that code from your link), any I,O,or Q will match in the negative character class. – Feb 16 '11 at 20:43

score 0 · Answer 2 · answered Feb 16 '11 at 20:36

Try this at home:

class Vin { 
   public static void main( String ... args ) { 
      String vin = "1M8GDM9A_KP042788";
      if(!vin.matches("[^\\Wioq]{17}")) { //the offending code, always fails
        System.out.println("vininfo did not pass regex");
      } else { 
        System.out.println("works");
     }
   }
}

Prints:

$java Vin 
works

You don't need the /^ and $/

regular expressions in Java

2 Answers2