This version

• reads the keys into an array
• reads items from standard input
• for each item, print if not found in the array

public class LinearSearch
{
   private static int rank(int[] keys, int item)
   {
     // linear search implementation above
     ...
   }

   public static void main(String[] args)
   {
     int[] keys = StdIn.readInts(args[0]);
     
     while(!StdIn.isEmpty()) {
       int item = StdIn.readInt();
       if ( rank(keys, item) == - 1 ) {
          System.out.println(item);
       }
     }
   }
}