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 common usage patterns of java.util.Map that could be replaced with Java 8 methods: getOrDefault(), computeIfAbsent(), putIfAbsent(), merge(), or replaceAll().
Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>
Reports the copying of array contents to a collection where each element is added individually using a for loop. Such constructs may be replaced by a call to Collection.addAll(Arrays.asList()) or Collections.addAll().
Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>
Reports explicit boxing, i.e. wrapping of primitive values in objects. Explicit manual boxing is unnecessary under Java 5 and newer, and can be safely removed.
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>
Andrey Turbanov
Andy Clement
Alexander Kriegisch
Jerry James
Lars Grefer