How do I return objects with lambdas java

Question

Say I have a List addressees, and the properties for the address are
1. ID
2. Name
3. State
Then I have a get method to get an address by ID

public Address get(Integer id) {
    for (Address myAddress : addresses) {
        if (myAddress.getId() == id) {
            return myAddress;
        }
    }
    return null;
}

This is how it would look without lambdas
How do I return the address using lambdas?

Possible duplicate: http://stackoverflow.com/questions/23696317/java-8-find-first-element-by-predicate — Sotirios Delimanolis, May 17 '16 at 21:36

Nicolas Filotto · Accepted Answer · 2016-05-17T21:49:16.460

It should according to your context something like:

// Find any address that matches
addresses.stream().filter(a -> a.getId() == id).findAny();

or

// Find the first address that matches
addresses.stream().filter(a -> a.getId() == id).findFirst();

The first approach is mostly interesting in case you want to parallelize the search using addresses.parallelStream().filter(a -> a.getId() == id).findAny(), it will be much faster than the second approach as it will stop seeking as soon as we have a result. The second approach is more interesting in case you don't intend to parallelize it which seems to be your case here.

So finally, it gives:

public Address get(Integer id) {
    return addresses.stream()
        .filter(a -> a.getId() == id)
        .findFirst().orElse(null);
}

Er, why wouldn't you write `return result.orElse(null)`? – Louis Wasserman May 17 '16 at 21:47 — Louis Wasserman, May 17 '16 at 21:47
Thankyou :) I was missing the findFirst at the end. – Brennan Bennett May 17 '16 at 21:58 — Brennan Bennett, May 17 '16 at 21:58

score 0 · Answer 2 · answered May 17 '16 at 21:50

0

I'll do this:

public Address get(Integer id) {
    return addresses.stream()
        .filter(a -> a.getId().equals(id))
        .findFirst()
        .orElse(null);
}

Cheers

answered May 17 '16 at 21:50

eric.v

605
5
9

ahhh I see, I was missing the findFirst() at the end. Also in your filter it should be getId() == id ;) but it works. thanks! – Brennan Bennett May 17 '16 at 21:54
1

Do you mean your Address object contains an id field of type int but your method signature is Integer id ? – eric.v May 17 '16 at 21:59
yeah sorry, I should of clarified that better. – Brennan Bennett May 17 '16 at 22:13

How do I return objects with lambdas java

2 Answers2