How do I get a key from a HashMap by providing the value?

Question

private static HashMap<Script, String> scripts = new HashMap<>();

    public Script getScriptByName(String name) {
        for (String s : scripts.values()) {
            if (s.equals(name)) {
                ...
            }
        }
        return null;
    }

Given this code, how can I get the key of a specific value?

If you need to do this, you should probably restructure your data. Perhaps point the map in the other direction? — user2357112, Apr 30 '14 at 21:51
Does it have to be a hashmap? See this answer: http://stackoverflow.com/questions/10699492/bi-directional-map-in-java — Daniel Kaplan, Apr 30 '14 at 21:51
possible duplicate of [Java Hashmap: How to get key from value?](http://stackoverflow.com/questions/1383797/java-hashmap-how-to-get-key-from-value) — Brian Roach, Apr 30 '14 at 22:01

score 6 · Accepted Answer · edited Apr 30 '14 at 22:07

6

Navigate through the entries of the map instead:

for (Map.Entry<String, String> entry : scripts.entrySet()) {
    if (entry.getValue().equals(name)) {
        return entry.getKey();
    }
}

return null;

edited Apr 30 '14 at 22:07

VH-NZZ

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answered Apr 30 '14 at 21:51

Luiggi Mendoza

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you're missing a `)` after `scripts.entrySet()`. I can't edit due to not changing up to 6 chars – Vince Apr 30 '14 at 21:54
@VinceEmigh WADR, after `equals(name)`? – VH-NZZ Apr 30 '14 at 22:07

How do I get a key from a HashMap by providing the value?

1 Answers1