Merge List and List into List>

Question

i have two list;

val keys: List<String> = listOf("key1", "key2", "key3"...)
val values: List<String> = listOf("value1", "value2", "value3"...)

How can i merge them into one List<Hashmap<Key,Value>>? like;

println(List<Hashmap<Key,Value>>): [[key1 = value1], [key2 = value2], [key3 = value3]...

Answer 1

In idiomatic Kotlin, that would look like this:

val keys: List<String> = listOf("key1", "key2", "key3")
val values: List<String> = listOf("value1", "value2", "value3")

val result = keys.zip(values).map { hashMapOf(it) }

^{(runnable demo)}

Here, hashMapOf(...) accepts pairs (Pair<K, V>), and that's exactly the elements that zip produces.

Alternatively, you can use the overload of zip that accepts a lambda and maps the pairs without an additional call to map:

val result = keys.zip(values) { k, v -> hashMapOf(k to v) }

^{(runnable demo)}

The result is a list of maps, each containing a single key mapped to the value.

---

An opposite option is to create a single map containing all of the pairs, which can be produced as follows:

val result = HashMap(keys.zip(values).toMap())

^{(runnable demo)}

Answer 2

I would have done like this. Create your own class

class MyMap{
   String key;
   String value;
}

and then

 List<MyMap> newList = new ArrayList<>();
for (int i=0;i<keys.size();i++){
      newList.add(new MyMap(keys.get(i),values.get(i)));
 }