Boxing a primitive using the constructor ("new Integer(4)") always
creates a distinct new boxed instance. That's rarely what you need,
and in fact all of those constructors have been deprecated in Java 9.
Using the static "valueOf" method instead ("Integer.valueOf(4)") can
give better performance by reusing existing instances. You no longer
get a unique boxed object, but generally that's OK.
Eclipse's automated code clean-up tool did most of the heavy lifting
here: it specifically has a clean-up option for converting functional
interfaces to lambdas. I merely had to revert the automated changes
for a single enumeration class for which it produced invalid results,
and for a few test inputs that apparently aren't set up to be compiled
with Java 8.
Most of these are harmless, and are best fixed simply by removing the
redundant check or assignment. The one in FlowType.compareBlocks,
however, revealed a real problem. This code checks for nullness of
`a` *after* having called a method on `a`. Assuming that `a` can
indeed be `null` here, the check must come first to avoid a
`NullPointerException`.
In several places, I saw code of this form:
if (thing == null)
assert thing != null : ... ;
I honestly don't understand the purpose of that `if` statement. Why
not just have the `assert` statement there directly? I removed the
seemingly irrelevant `if` statements in these cases, but if this is
some intentional pattern, please explain it to me.
In a few places where nullness is statically known but non-obvious,
add assert statements to point out what's going on to help future
developers.
Upgrade future such warnings to errors to keep us moving in a cleaner
direction.
In general, my approach was to try to eliminate each unused parameter
using Eclipse's "Change Method Signature" refactoring. That did not
always succeed: a parameter may be unused in some base class method,
but then be used in subclass's override of that method. In cases
where refactoring to eliminate a parameter failed, I instead annotated
the parameter with '@SuppressWarnings("unused")' to silence the
warning.
Note: this group of changes creates a significant risk of
incompatibility for third-party WALA code. Some removed parameters
change externally-visible APIs. Furthermore, these changes do not
necessarily lead to Java compilation errors. For example, suppose
third-party code subclasses a WALA class or interface, overrides a
method, but does not annotate that method as @Override. Removing a
parameter means that the third-party method no longer overrides. This
can quietly change code behavior without compile-time errors or
warnings. This is exactly why one should use @Override wherever
possible, but we cannot guarantee that third-party WALA users have
done that.
I have *not* upgraded this problem to be treated as an error in the
future. Unfortunately Eclipse uses a single configuration setting for
both unnecessary semicolons and also for empty control-flow statements
like `while (p) ;`. I'm not convinced that it's worth rewriting all
instances of the latter into `while (p) { }`. So this is just going
to stay as a warning for now.
The fix is to add "static" where appropriate, of course. I've also
simplified calls to such methods to reflect the fact that they no
longer need a specific object to call the method on.
In projects that contain test inputs, I've left the non-static
declarations unchanged, and instead downgraded the warning to be
ignored. In all other projects, this warning has been upgraded to an
error.
* Fix warnings about unset javacProjectSettings build entries
Specifically, these are all warnings of the form "The
'javacProjectSettings' build entry should be set when there are project
specific compiler settings".
* Add @Override annotations to all methods that do override
This fixes 287 Eclipse code style warnings.
* Cannot add @Override annotations here, so suppress warnings instead
We should be able to add these @Override annotations in the future,
one Eclipse Mars and earlier are no longer supported. For now,
though, they have to go away in order to be compatible with older
Eclipse releases.
In the cases addressed here, the caught exception was being "handled"
by throwing some new exception. Instead of discarding the old
exception, pass it to the new exception's constructor to indicate the
original cause of the newly-created exception. This practice, called
"exception chaining", can often be useful in debugging.
The contents of @author go straight into HTML, just like most other
Javadoc material. So if you want to have a "<foo@bar.com>" e-mail
address as part of the author information, the angle brackets must be
escaped. Here I've opted to do that using "{@code <foo@bar.com>}",
which has some additional styling effects that seem appropriate for
e-mail addresses. We could also have used "<foo@bar.com>" for
escaping without code styling.
Julian Dolby
Ben Liblit
Martin Mohr
Manu Sridharan
steohan
Stephan Gocht
Julian Dolby