Yeah, this basically hides the unsafe cast in the implementation of 
Class#cast(..). It has its advantages and disadvantages:

Pro: Performs an additional dynamic Class#isInstance(..) check that throws 
a CCE at the place where the unsafe cast happens => fail-fast is good 
(although the cast at the caller side also won't be far away; and that's 
how it used to work in the past).

Contra: Is less explicit than the SuppressWarnings version, since the type 
safety problem is not immediately visible at the code location where the 
unchecked cast happens.

=> adapter.cast(..) is OK for me, but not a must.

Markus



From:   "Andrey Loskutov" <[email protected]>
To:     [email protected]
Cc:     "General development mailing list of the Eclipse project." 
<[email protected]>, Cross project issues 
<[email protected]>
Date:   2015-02-20 15:35
Subject:        Re: [cross-project-issues-dev] org.eclipse.equinox.common 
has added generics to API in org.eclipse.core.runtime package
Sent by:        [email protected]



Hi,
Before everyone starts to change getAdapter() implementation, please 
consider to user warning-free alternative:
 
Instead of writing:
 
        @SuppressWarnings("unchecked")
        public <T> T getAdapter(Class<T> adapter) {
                if (ICompilationUnit.class.equals(adapter))
                        return (T) getCompilationUnit();
                return null;
        }
 
use Class.cast() API:

        public <T> T getAdapter(Class<T> adapter) {
                if (ICompilationUnit.class.equals(adapter))
                        return adapter.cast(getCompilationUnit());
                return null;
        }
 
Kind regards,
Andrey Loskutov

http://google.com/+AndreyLoskutov
 
 
Gesendet: Freitag, 20. Februar 2015 um 15:21 Uhr
Von: "Thomas Watson" <[email protected]>
An: "Cross project issues" <[email protected]>, 
"General development mailing list of the Eclipse project." 
<[email protected]>
Betreff: [cross-project-issues-dev] org.eclipse.equinox.common has added 
generics to API in org.eclipse.core.runtime package
See https://bugs.eclipse.org/bugs/show_bug.cgi?id=442021

Markus Keller wrote up an nice summary of what consumers should do to fix 
any warnings that may be caused by this change at 
https://bugs.eclipse.org/bugs/show_bug.cgi?id=442021#c25

Here is a copy of the recommendations if you are going to compile against 
the latest version of org.eclipse.equinox.common:

1. In MANIFEST.MF, update your Require-Bundle: 
org.eclipse.core.runtime;bundle-version="[3.11.0,4.0.0)", or 
org.eclipse.equinox.common;bundle-version="[3.7.0,4.0.0)", or update your 
Import-Package: org.eclipse.core.runtime; version="[3.5,4.0)"

2. If your bundle re-exports one of these bundles, then you also have to 
make sure the minor version is incremented.

3. Remove unnecessary casts (Clean Up, or Problems view > Quick Fix > 
Select All)

4. Update implementations of IAdaptable#getAdapter(Class<T>), unless you 
override another implementation of that method that still uses the old 
signature.

Typical change:
Old:
        public Object getAdapter(Class adapter) {
                if (ICompilationUnit.class.equals(adapter))
                        return getCompilationUnit();
                return null;
        }

New:
        @SuppressWarnings("unchecked")
        public <T> T getAdapter(Class<T> adapter) {
                if (ICompilationUnit.class.equals(adapter))
                        return (T) getCompilationUnit();
                return null;
        }

5. Update implementations of IAdapterFactory

Hint for 4. & 5.:
- Open Type Hierarchy on IAdaptable, etc.
- In the view menu, select a working set that contains your projects
- In the methods list of the Type Hierarchy view, select the methods, and 
then click the first toolbar button (Lock View and Show Members in 
Hierarchy)


Tom

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