Retrieve value from hashmap and return

Question

How to write code for the following logic in Java-8, here is my code

private static Integer getTheInteger() {
    Map<String, Integer> items = new HashMap<>();
    items.put("A", 10);
    items.put("B", 20);
    items.put("C", 30);
    items.put("D", 40);
    items.put("E", 50);
    items.put("F", 60);

    for (Map.Entry<String, Integer> entry : items.entrySet()) {
        if(entry.getKey().equals("E")) {
            return entry.getValue();
        }
    }
    return 0;
}

For records, do take a look at [What should I do when someone answers my question?](https://stackoverflow.com/users/9110949/aruntheimperfect) — Naman, Dec 24 '18 at 11:44

Naman · Answer 1 · 2018-12-24T18:18:04.137

4

You just need a get for it ideally. Additionally, to handle a default case(return 0 here) use Map.getOrDefault as in :

return items.getOrDefault("E", 0);

edited Dec 24 '18 at 18:18

answered Dec 24 '18 at 09:15

Naman

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This helps you from avoiding to create unnecessary `Optional` or even helps readability as compared to a branching. – Naman Dec 24 '18 at 09:21
1

very nice indeed, I seem to forget `getOrDefault` almost every time... – Ousmane D. Dec 24 '18 at 09:25

score 1 · Answer 2 · answered Dec 24 '18 at 09:14

1

You don't need a loop for that, and you don't need any Java 8 functionality.

return items.get("E");

Or, to handle the 0 value when key is not in the Map:

return items.containsKey("E") ? items.get("E") : 0;

answered Dec 24 '18 at 09:14

Eran

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I guess I would find [`getOrDefault`](https://stackoverflow.com/a/53911413/1746118) better (opinion based), which though under the cover does the same check. – Naman Dec 24 '18 at 09:18

Ousmane D. · Answer 3 · 2018-12-24T09:22:32.360

if you were to use a stream for this it would look like:

return items.entrySet()
            .stream()
            .filter(s -> "E".equals(s.getKey()))
            .findFirst().map(Map.Entry::getValue)
            .orElse(0);

but a better approach would be not to iterate over the map entries but instead use get() and depending on the result provide a default value.

return Optional.ofNullable(items.get("E")).orElse(0);

Retrieve value from hashmap and return

3 Answers3