How does one make a HashMap from two ArrayLists?

Question

I have two ArrayLists:

ArrayList<Integer> keySet = new ArrayList<Integer>();

and

ArrayList<String> values = new ArrayList<String>();

How would I create a HashMap using the keySet ArrayList as the keyset in the hashmap and the values ArrayList as the values in the HashMap?

Be careful, the question smells a little bit of misunderstanding HashMap. A key is always associated with the value you give it. The answer below will associate them by their index order, but any modifications after that and the two collections will diverge. HashMap alone also does not preserve order, your keys won't necessarily print in the same order you put them in. — Rogue
– Rogue, Commented Aug 14, 2019 at 20:16

nishantc1527 · Accepted Answer · 2019-08-14 20:04:30Z

3

Assuming the length is the same:

HashMap<Integer, String> a = new HashMap<>();
for(int i = 0; i < keySet.size(); i++) {
    a.put(keySet.get(i), values.get(i));
}

answered Aug 14, 2019 at 20:04

nishantc1527

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