Question

I’m trying to select and get values from customer objects. What I want to do is to enter a personal number like “702312” and search after the customer objects that has a data member personal number that are equal to “702312”. And when I found it I want to get the rest of the values or change it’s content. This is some code that creates the customer objects from the class Customer and then it’s stored in a arraylist.

// create a new customer object and send personal number, name and account number to constructor
Customer customer = new Customer(personalNumber, name, newAccountNumber);

// create an arraylist to store customer objects
ArrayList<Customer> customerList = new ArrayList<Customer>();

// add the new customer object to arraylist that holds all customer objects
customerList.add(customer);

I have tried to reach the values like this, but it’s not working, so I’m looking for some help?

 // search for customer
 for (Customer customer : customerList) {
if(customer.getAccountOwnerPersonalNumber() == "702312"){
    System.out.println("OK!!!");
    }
 }

And instead of:

 if(customer.getAccountOwnerPersonalNumber() == "702312")...

I have tried this:

 if(customer.personalNumber == "702312")...

Finally I have also tested it like this:

for(int i=0;i<customerList.size();i++){
    if(customerList.get(i).getAccountOwnerName() == "702312");
    System.out.println("OK");
    break;
}

I’m not sure if I’m doing right!? Help is preciated! Thanks!

Answer 1

You need to use the equals() method to compare objects like Strings by their internal value (otherwise they will only be compared by reference):

if (customer.getAccountOwnerPersonalNumber().equals("702312")) {
    System.out.println("OK!!!");
}

or, better, if it can potentially return null:

if ("702312".equals(customer.getAccountOwnerPersonalNumber())) {
    System.out.println("OK!!!");
}

or, if applicable, just make it a primitive like int, so that == will work the way you intended:

private int accountOwnerPersonalNumber;

with

if (customer.getAccountOwnerPersonalNumber() == 702312) {
    System.out.println("OK!!!");
}