StringBuffer is a legacy synchronized class. StringBuilder is a direct replacement to StringBuffer which generally have better performance.

This was required by the Eclipse team as one precondition for the next
release.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Reports on declarations of Collection variables made by using the collection class as the type, rather than an appropriate interface.

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Reports Collection.addAll() and Map.putAll() calls after instantiation of a collection using a constructor call without arguments. Such constructs can be replaced with a single call to a parametrized constructor which simplifies code. Also for some collections the replacement might be more performant.

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

There are two styles to convert a collection to an array: either using a pre-sized array (like c.toArray(new String[c.size()])) or using an empty array (like c.toArray(new String[0]).
In older Java versions using pre-sized array was recommended, as the reflection call which is necessary to create an array of proper size was quite slow. However since late updates of OpenJDK 6 this call was intrinsified, making the performance of the empty array version the same and sometimes even better, compared to the pre-sized version. Also passing pre-sized array is dangerous for a concurrent or synchronized collection as a data race is possible between the size and toArray call which may result in extra nulls at the end of the array, if the collection was concurrently shrunk during the operation.

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Reports calls to Collections.sort(list, comparator) which could be replaced with list.sort(comparator).

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Reports for loops which iterate over collections or arrays, and can be replaced with an enhanced for loop (i.e. the foreach iteration syntax).

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

removed unused imports, local variables, and private methods
(still there, just commented out).

The basic structure and examples of each type are there, 
but I have more examples and the ones there are not 
altogether validated.  I'll make a few more changes 
before emailing dev and users about usage, etc.