CustomerDataService

package com.mycompany.client;

import java.util.ArrayList;
import java.util.List;

public class CustomerDataService {
    public List<Customer> customerList=new ArrayList<>();
    Customer e=new Customer();
    public CustomerDataService(){
        e.setAddress("Hatay/Antakya");
        e.setId("0");
        e.setName("Gokhan");
        e.setPhoneNumber("15134235322452");
        customerList.add(e);
    }
    private static CustomerDataService ourInstance=new
        CustomerDataService();
    public static CustomerDataService getInstance(){
        return ourInstance;
    }
    public String addCustomer(Customer customer){
        String newId=Integer.toString(customerList.size()+1);
        customer.setId(newId);
        customerList.add(customer);
        return newId;
    }
    public List<Customer> getCustomerList(){
        return customerList;
    }
    public Customer getCustomerById(String id) {
        for (Customer customer : customerList) {
            if (customer.getId().equals(id)) {
                return customer;
            }
        }
        return null;
    }
}