Memory

'StringBuilder' field  

Reports fields of type java.lang.StringBuffer or java.lang.StringBuilder.

Anonymous class may be a named 'static' inner class  

Reports anonymous classes that may be safely replaced with static inner classes.

Call to 'System.gc()' or 'Runtime.gc()'  

Reports System.gc() or Runtime.gc() calls.

Inner class may be 'static'  

Reports inner classes that can be made static.

Return of instance of anonymous, local or inner class  

Reports return statements that return an instance of an anonymous, local, or inner class.

Static collection  

Reports static fields of a Collection type.

Unnecessary zero length array usage  

Reports allocations of arrays with known lengths of zero when there is a constant for that in the class of the array's element type.

Zero-length array allocation  

Reports allocations of arrays with known lengths of zero.