Java8 stream filter by multiple parameters

Question

I have the following class:

public class Transfer {
    private String fromAccountID;
    private String toAccountID;
    private double amount;
}

and a List of Transfers:

....
private List<Transfer> transfers = new ArrayList<>();

I know how to get one transfer history:

transfers.stream().filter(transfer -> 
    transfer.getFromAccountID().equals(id)).findFirst().get();

But I want to get by fromAccountID and toAccountID, so the result will be a List of Transfers. How can I do that with Java8 Stream filter functions?

you should never call get() straight from an optional result except in cases where you know there will be a value present. rather you should utilise orElse or orElseGet depending on which is most appropriate for your case — Ousmane D.
– Ousmane D., Commented Dec 25, 2017 at 19:36
your advise was really helpful today, get() threw an exception, in order to handle it, I've used orElse and check it if it is null. Cheers! — Sarvar Nishonboyev
– Sarvar Nishonboyev, Commented Dec 26, 2017 at 18:53

indivisible · Accepted Answer · 2018-10-08 10:58:30Z

7

filter by the two properties and collect into a list.

List<Transfer> resultSet = 
      transfers.stream().filter(t -> id.equals(t.getFromAccountID()) || 
                        id.equals(t.toAccountID()))
               .collect(Collectors.toList());

edited Oct 8, 2018 at 10:58

indivisible

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answered Dec 25, 2017 at 19:19

Ousmane D.

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Comments

Eran · Accepted Answer · 2017-12-25 19:19:36Z

5

You can filter by both properties (getFromAccountID() and getToAccountID()), and collect the elements that pass the filter to a List:

List<Transfer> filtered = 
    transfers.stream()
             .filter(t -> t.getFromAccountID().equals(id) || t.getToAccountID().equals(id))
             .collect(Collectors.toList());

answered Dec 25, 2017 at 19:19

Eran

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