Help, still trying to get the basics of Java

Question

OK, I'm still trying to figure out the basics and on this program decided to write small amounts of code at a time and compile them so I could learn where I was making the mistakes. I keep getting stuck I am getting 5 cannot find symbols on the following code. I've made sure I have imported the Scanner class, checked my brackets, but can't figure out why it is still giving these errors. Can you please help? Why will it not recognize "input"?
import java.util.Scanner;
public class Inventory
     public static void main( String args[] )
     String productNum = "";
     String name = "";
     int units = 0;
     double amount = 0;
     Scanner scan = new Scanner( System.in );
     System.out.println ( "Please enter product #" );
     productNum = input.next();
     System.out.println ( "Please enter color name" );
     name = input.next();
     System.out.println ( "Please enter units on hand" );
     units = input.nextInt();
     System.out.println ( "Please enter dollar amount for each unit" );
     amount = input.nextDouble();
     System.out.println (productNum, name, units, amount);
}

Answer 1

Doesn't it not mean that your AlbumInventory class does not define a constructor that takes zero arguments?
e.g
public class AlbumInventory {
     public static void main(String [] args) {
         AlbumInventory brokenInventory  = new AlbumInventory(); // This will produce compile error
         AlbumInventory workingInventory = new AlbumInventory(5098) // This will compile
     private int id;
     public AlbumInventory (int id) {
          this.id = id;
}