Question

Here is my problem:
my function in class A:

public void setData(Map<String,? extends ArrayList<? extends SomeInterface>>){...}

my call:

Map<String, ArrayList<ImplementsSomeInterface>> a=...;
instanceOfA.setData(a); //does not compile
instanceOfA.setData((Map<String,? extends ArrayList<? extends SomeInterface>>) a); // works thanks to the Casting.

I don’t think this is clean. Is there a way to avoid the casting without droping the wildcard use in the function?

Answer 1

First your setData method should read:

public void setData(Map<String,? extends List<? extends SomeInterface>>)

Your map declaration should read:

Map<String, List<ImplementsSomeInterface>> a = ...;

Which is pretty much what you’ve got following your edits to the original question. The change I’ve made from ArrayList to List doesn’t effect the behaviour of the code.

Following comments:

public static void main() 
{
    Map<String, List<Double>> map = new HashMap<String, List<Double>>();
    map.put("prices", new ArrayList<Double>(Arrays.asList(1.1, 2.2, 3.3)));

    setData(map);
}

public static void setData(Map<String,? extends List<? extends Serializable>> map)      
{
}