Known Type Changes

List of type changes and the known reasons for performing them (from literature and developer documentation)

Type From	Type To	# Projects	# Commits	# Instances	Known Reasons
int	long	75	623	4600	Primitive Widening
int	double	22	47	115	Primitive Widening
java.util.List	java.util.Set	68	281	742	Different Properties
java.util.LinkedList	java.util.DeQue	8	8	19	Different Properties
java.util.ArrayList	java.util.List	52	152	560	Use Supertype When Possible (Effective Java)
java.util.HashMap	java.util.Map	38	112	348	Use Supertype When Possible (Effective Java)
java.util.Map	java.util.concurrent.ConcurrentMap	37	93	139	Concurrency (Dig et al.)
int	java.util.concurrent.atomic.AtomicInteger	32	65	86	Concurrency (Dig et al.)
java.lang.StringBuffer	java.lang.StringBuilder	38	109	280	Performance
java.util.concurrent.atomic.AtomicLong	java.util.concurrent.atomic.LongAdder	11	16	227	Performance
java.util.List	com.google.collect.ImmutableList	18	66	145	Immutability
java.util.Set	com.google.collect.ImmutableSet	9	50	95	Immutability
java.lang.String	java.nio.file.Path	23	56	502	Conceptual Types (Dash et al.)
long	java.util.Date	2	2	9	Conceptual Types (Dash et al.)
org.apache.commons.logging.Log	org.sl4fj.Logger	8	123	1902	Third party library migration (Alurbaye et al.)
org.mongodb.BasicDbObject	org.bson.Document	3	3	37	Third party library migration (Alurbaye et al.)
java.util.Random	java.security.SecureRandom	6	6	8	Security
java.lang.String	java.security.Key	2	2	2	Security
org.joda.time.DateTime	java.time.ZonedDateTime	5	6	126	Deprecation