Linked List only working with 1st linked list

Question

So I am trying to view all data in the Linkedlist in java. They Look like this:

private List <Customer> customers;
public databse(){
customers.add(new Customer(101, "Allen", 10))
customers.add (new Customer(102, "John", 15))
customers.add (new Customer(103, "Lucy", 23))
}

Then i am trying to view the customer based on th id by using this

   private void customer(){
   System.out.println(" ");
   System.out.print("Enter a customer ID: ");
   int id = In.nextInt();
   for(Customer customer:customers )
   {
        if(customer.getID() == id){
            System.out.println(customer.toString());
            System.out.println(" ");
           // break;
          }
          else 
        {System.out.println("That customer does not exist.");
        System.out.println(" ");

        }
        System.out.println(" ");
     break;           
   }

Then i get this as an output:

Enter a customer ID: 101
101 Allen   10

However, if I try to view 102 or 103 it doesn't work

Enter a customer ID: 102 
That customer does not exist.

What might be the problem? Allen and Customers classes are already called.

Answer 1

The problem is in your loop where you check the first element and then either print it or `breakout of the loop. The rest of your items are never checked.

Instead you should keep track of if an object was found or not.

private void customer(){
    System.out.println(" ");
    System.out.print("Enter a customer ID: ");
    int id = In.nextInt();
    boolean found = false;
    for(Customer customer:customers ) {
        if(customer.getID() == id){
            System.out.println(customer.toString());
            System.out.println(" ");
            found = true;
            break;
        }
    }
    if (!found) {
        System.out.println("That customer does not exist.");
        System.out.println(" ");
    }
}

Answer 2

You did a break at the end of the for, handling only the first customer. Handle the result after the loop.

Optional<Customer> foundCustomer = Optional.empty();
for (Customer customer : customers) {
    if (customer.getID() == id) {
        foundCustomer = Optional.of(customer);
        break;
    }
}

Or

Optional<Customer> foundCustomer = customers.stream().findAny(c -> c.getID() == id);

and then

if (foundCustomer.isPresent()) {
    System.out.println(foundCustomer.get());
} else {
    System.out.println("That customer does not exist.");
}