How does one convert a HashMap to a List in Java?

Question

In Java, how does one get the values of a HashMap returned as a List?

Answer 1

If you wanna maintain the same order in your list, say: your Map looks like:

map.put(1, "msg1")
map.put(2, "msg2")
map.put(3, "msg3")

and you want your list looks like

["msg1", "msg2", "msg3"]   // same order as the map

you will have to iterate through the Map:

// sort your map based on key, otherwise you will get IndexOutofBoundException
Map treeMap = new TreeMap(map)

List list = new List();
for (treeMap.Entry entry : treeMap.entrySet()) {
    list.add(entry.getKey(), entry.getValue());
}