title: ArrayList related debugging question
body: <p>Please help me explaning this. I can't seem to figure out why this produce a null pointer exception</p>
  
  <pre><code>/* Try to find customer in customer list, if not in list add to list with a 
  new plan; otherwise add additional plan to customer*/
  
  
  for(int a = 0; a &lt; dataset.length; a++){
  
         if(customer_name_list.contains(dataset[a][CLIENT_NAME])){
              int temp_index = 0;
  
  //NULLPOINTEREXCEPTION OCCURRED ON THE FOLLOWING LINE 
              while(!customer.get(temp_index).name.equals(dataset[a][CLIENT_NAME])){
                  temp_index++;
              }
              customer.get(temp_index).add_plan(dataset[a][PLAN], dataset[a][DETAIL]);
         }
  
         else{
                  Customer temp_customer = new Customer(dataset[a][CLIENT_NAME], dataset[a][PLAN], dataset[a][DETAIL]);
  
         customer.add(temp_customer);
         customer_name_list.add(dataset[a][CLIENT_NAME]);
         }
     }
  </code></pre>
  
  <p>Thank you for your help</p>