Java Generics non-issue at compile time

Question

The code below compiles without error... for once I would have preferred it to fail :/

    Map <Character, Double> m = new HashMap <Character, Double>();
    m.get(new String());

Since the compiler knows that the key used in this map is of type Character, using a String key instead should be flagged as incorrect.

What I am missing ?

Answer 1

You're not missing anything. All Map#get() calls simply take Object.

Depending on the implementation, you might see a (runtime) ClassCastException when you pass a String to a Map<Character, Double>#get().

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Here's why Map#get() isn't fully generic.

Answer 2

You're missing an (optional) run-time exception (ClassCastException), if you try running this code.