So I have a hashmap<x,y> myHashmap
x implements z.
I want to get an iterator for z.
Since x is a "child" of z, this shouldn't be hard, but I can't think of how to do it.
My attempt:
return (Iterator<z>) this.myHashmap.keySet().iterator();
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User
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Why do you need this? – Tim Biegeleisen Nov 02 '16 at 01:38
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@TimBiegeleisen Trying to implement a function with a set return type. – User Nov 02 '16 at 01:40
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You can refer to this: (http://stackoverflow.com/questions/10581561/best-way-to-cast-iteratorobject-to-a-setstring-for-instance). – KC Wong Nov 02 '16 at 01:41
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`Collections.unmodifiableMap(this.myHashmap).keySet().iterator()`. – Louis Wasserman Nov 02 '16 at 01:44
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@KCWong That's the wrong direction. – User Nov 02 '16 at 01:45
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@LouisWasserman That doesn't change anything. How do I change to hashmap
? – User Nov 02 '16 at 01:46 -
@User: So just swap the classes? That SO thread means there's no way to cast an Iterator. You construct a new map and move the items over. – KC Wong Nov 02 '16 at 01:48
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@User `Collections.unmodifiableMap` lets you turn a `Map
` into a `Map – Louis Wasserman Nov 02 '16 at 02:05`. You might need explicit generics, though.