Update CheckDigit.java

src/main/java/CheckDigit.java

@@ -1,13 +1,17 @@
 public class CheckDigit 
 {   
   /** Returns the check digit for num, as described in part (a).  
-   *  Precondition: The number of digits in num is between one and    
+   *  Precondition: The number of digits in num is between one and    
    *  six, inclusive.  
    *          num >= 0  
    */  
    public static int getCheck(int num) 
    {  
-     /* to be implemented in part (a) */
+     int count = 0;
+     for ( int i = 1; i <= getNumberOfDigits(num);i++){
+       count = count + ((8-i) * getDigit(num, i));
+     }
+     return count % 10;
    }
 
   /** Returns true if numWithCheckDigit is valid, or false    
@@ -18,7 +22,14 @@ public static int getCheck(int num)
    */     
    public static boolean isValid(int numWithCheckDigit)    
    {      
-     /* to be implemented in part (b) */    
+     int check = numWithCheckDigit % 10;
+     int num = numWithCheckDigit/10;
+     int newCheck = getCheck(num);
+     if (check == newCheck){
+       return true;
+     }else{
+     return false;
+     }
    }    
 
    /** Returns the number of digits in num. */