Get keys from HashMap in Java

data-structures, java, java-6

Solution

A `HashMap` contains more than one key. You can use `keySet()` to get the set of all keys.

team1.put("foo", 1);
team1.put("bar", 2);

will store `1` with key `"foo"` and `2` with key `"bar"`. To iterate over all the keys:

for ( String key : team1.keySet() ) {
    System.out.println( key );
}

will print `"foo"` and `"bar"`.

Problem

I have a Hashmap in Java like this: ``` private Map<String, Integer> team1 = new HashMap<String, Integer>(); ``` Then I fill it like this: ``` team1.put("United", 5); ``` How can I get the keys? Something like: `team1.getKey()` to return "United".

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