How do I keep the iteration order of a List when using Collections.toMap() on a stream?

Question

I am creating a Map from a List as follows:

List strings = Arrays.asList(\"a\", \"bb\", \"ccc\");

Map

        

Answer 1

Simple function to map array of objects by some field:

public static  Map toLinkedHashMap(List list, Function someFunction) {
    return list.stream()
               .collect(Collectors.toMap(
                   someFunction, 
                   myObject -> myObject, 
                   (key1, key2) -> key1, 
                   LinkedHashMap::new)
               );
}


Map myObjectsByIdMap1 = toLinkedHashMap(
                listOfMyObjects, 
                MyObject::getSomeStringField()
);

Map myObjectsByIdMap2 = toLinkedHashMap(
                listOfMyObjects, 
                MyObject::getSomeIntegerField()
);