title: how to generate a random numbers for a credit card
body: <p>I created a code to generate a random credit card number and I'm using this method to return a credit card number based in the user input. For some reason I am having a problem returning a value. Help please.</p>
  
  <pre><code> public String getIssuerCode(String issuerSymbol) {
          String creditCardNumber = null;
  
          for (int i = 0; i &lt; 15; i++) {
  
              switch (issuerSymbol) {
                  case ISSUER_MASTER_CARD:
  
                    creditCardNumber   = generateMasterCard();
                      break;
                  case ISSUER_AMER_EXPRESS:
               creditCardNumber   = generateAmericanExpress();
                      break;
                  case ISSUER_VISA:
                   creditCardNumber   = generateVisa();
                      break;
                  // System.out.println("error");
                  default:
                      break;
              }
  
          }
  
          return creditCardNumber;
      }
  </code></pre>