Bug 358209

Description Ben Davis 2011-09-20 05:51:58 EDT

Build Identifier: 20110615-0604

Map.get(), Map.remove(), Set.contains(), and many similar functions take 'Object' even if the collection is parameterised with a more specific key. I understand there's a reason for this, but I rarely want to pass any other type to these functions, so I would find it useful if Eclipse could warn me when I do it accidentally.

There are two cases: passing a potentially compatible type (where casting would be valid), and passing an incompatible type (where casting wouldn't be valid). These could be separate warnings if you like.

Reproducible: Always

Steps to Reproduce:
Example code that I'd like to see warnings for:

class C {}
interface I {}

void method(
    HashMap<C,Object> map,
    C compatibleKey,
    Object potentiallyCompatibleKey1,
    I potentiallyCompatibleKey2,
    String incompatibleKey
) {
    Object o;
    o=map.get(compatibleKey);
    o=map.get(potentiallyCompatibleKey1);  //"potentially incompatible key" warning
    o=map.get(potentiallyCompatibleKey2);  //"potentially incompatible key" warning
    o=map.get(incompatibleKey);  //"incompatible key" warning
}

Obviously there are more methods to think about than just HashMap.get; and there are cases involving wildcards that would need some thought; but even if this is just implemented for non-wildcard keys, that would cover most of the cases I encounter in my code :)

Thanks in advance!