Add, Delete and find using HashMap

Question

Hi I am using HashMap to add, find and remove Customers. I want them to be in separate classes to use the concept of divide-and-conquer, but I am failing to find and remove the customers. I was even suggested to loop the findCustomer to retrieve all the details.

  public static void addCustomer(){
       // Customers
    Map<String, Customer> customers = new HashMap<> ();
    customers.put ("ID1", new Customer ("Jonathan", "Mifsud", "Test Address", 21345678, "L001"));
    customers.put ("ID2", new Customer ("David", "Aguis", "2nd Address", 21456778, "L002"));
    customers.put ("ID3", new Customer ("Frank", "Mamo", "example Address", 21987653, "L003"));
  }

  public static void findCustomer(){
      //retrieve Customer Details
    System.out.println("Customer with ID1 is " + customers.get("ID1"));
  }

  public static void deleteCustomer(){
      //remove Customer Details
    System.out.println("Customer Deleted is ID3 " + customers.remove("ID3"));
  }

Your customers map in your addCustomer certainly shadow the static one you defined elsewhere. — Alexis C.
– Alexis C., Commented Apr 17, 2014 at 13:03

Joffrey · Accepted Answer · 2014-04-17 13:14:50Z

1

Your declaration of your map is misplaced, it is not currently visible to findCustomer and deleteCustomer methods. Don't you have a compile error in these 2 methods?

You should declare it as a field above the 3 methods, like this:

  private static Map<String, Customer> customers = new HashMap<> ();

  public static void addCustomer(){
       // Customers
    customers.put ("ID1", new Customer ("Jonathan", "Mifsud", "Test Address", 21345678, "L001"));
    customers.put ("ID2", new Customer ("David", "Aguis", "2nd Address", 21456778, "L002"));
    customers.put ("ID3", new Customer ("Frank", "Mamo", "example Address", 21987653, "L003"));
  }

  public static void findCustomer(){
      //retrieve Customer Details
    System.out.println("Customer with ID1 is " + customers.get("ID1"));
  }

  public static void deleteCustomer(){
      //remove Customer Details
    System.out.println("Customer Deleted is ID3 " + customers.remove("ID3"));
  }

Also, note that putting everything static might not be wise, especially if you start working with a state.

answered Apr 17, 2014 at 13:14

Joffrey

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1 Comment

Joffrey Over a year ago

Yes, you should remove all these static keywords and use an instance of the class instead.

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