The document describes a tool called "Convert Constants to Enum" that automatically converts Java constants to enumerated types. It presents a motivating example of code using constant integers for traffic light and automobile states that could be improved by using enums. The tool is demonstrated converting the example code to use enums, providing benefits like type safety and avoiding issues with the previous "weak enum pattern". The goal is to help developers take advantage of Java 5's new enum features by migrating legacy code.

1. Enumeration Refactoring: A Tool for
Automatically Converting Java
Constants to Enumerated Types
Raffi Khatchadourian (Ohio State University)
Benjamin Muskalla (EclipseSource)

2. Introduction

3. Introduction
• Java 5 introduced a rich set of new features such as
generics, metadata annotations, boxing/unboxing,
and type-safe enumerations.

4. Introduction
• Java 5 introduced a rich set of new features such as
generics, metadata annotations, boxing/unboxing,
and type-safe enumerations.
• Overview an automated semantics-preserving type
inference approach for migrating legacy Java code to
take advantage of the new language enumerated type
constructs.

5. Introduction
• Java 5 introduced a rich set of new features such as
generics, metadata annotations, boxing/unboxing,
and type-safe enumerations.
• Overview an automated semantics-preserving type
inference approach for migrating legacy Java code to
take advantage of the new language enumerated type
constructs.
• Briefly demonstrate an Eclipse IDE plugin refactoring
tool research prototype called CONVERT CONSTANTS TO
ENUM.

6. Introduction
• Java 5 introduced a rich set of new features such as
generics, metadata annotations, boxing/unboxing,
and type-safe enumerations.
• Overview an automated semantics-preserving type
inference approach for migrating legacy Java code to
take advantage of the new language enumerated type
constructs.
• Briefly demonstrate an Eclipse IDE plugin refactoring
tool research prototype called CONVERT CONSTANTS TO
ENUM.
• In progress to be included with the standard
distribution of Eclipse.

7. Motivating Example
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
private int color = RED;
/∗ Accessor for the light’s current color ∗/
public int getColor() {return this.color;}}
class Automobile {
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

8. Motivating Example
Weak Enum
Pattern
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
private int color = RED;
/∗ Accessor for the light’s current color ∗/
public int getColor() {return this.color;}}
class Automobile {
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

9. Motivating Example
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
private int color = RED;
/∗ Accessor for the light’s current color ∗/
public int getColor() {return this.color;}}
class Automobile {
Type Safety
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

10. Motivating Example
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
Manual
private int color = RED;
Enumeration
/∗ Accessor for the light’s current color ∗/
public int getColor() {return this.color;}}
class Automobile {
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

11. Motivating Example
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
private int color = RED;
/∗ Accessor for the light’s current color ∗/
Namespacing
public int getColor() {return this.color;}}
class Automobile {
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

12. Motivating Example
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
private int color = RED; Brittle
/∗ Accessor for the light’s current color ∗/
public int getColor() {return this.color;}}
class Automobile {
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

13. Motivating Example
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
private int color = RED;
/∗ Accessor for the light’s current color ∗/
public int getColor() {return this.color;}}
class Automobile {
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

14. Motivating Example Revisited
class TrafficSignal {
public static final int RED = 0;
public static final int YELLOW = 1;
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red by default ∗/
private int color = RED;
/∗ Accessor for the light’s current color ∗/
public int getColor() {return this.color;}}
class Automobile {
private static final int IDLE = 0;
private static final int INCREASE_SPEED = 1;
private static final int DECREASE_SPEED = 2;
private static final int STOP = 3;

15. Motivating Example Revisited
class TrafficSignal {{
TrafficSignal
public enum Color {RED, RED = 0;
public static final int
YELLOW,
public static final int YELLOW = 1;
GREEN};
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public int getColor() {return this.color;}}
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private static final int
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
private static final int MAX_SPEED = 140;
private
static final int STOP = 3;

16. Motivating Example Revisited
class TrafficSignal {{
class TrafficSignal
public enum Color {RED, RED = 0;
public static final int
YELLOW,
public static final int YELLOW = 1;
GREEN};
public static final int GREEN = 2;
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public int getColor() {return this.color;}}
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private static final int
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
private static final int MAX_SPEED = 140;
private
static final int STOP = 3;

17. Motivating Example Revisited
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN};
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red by default */
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public Color getColor() {return this.color;}}
int getColor() {return this.color;}}
class Automobile {
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

18. Motivating Example Revisited
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN};
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red by default */
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public Color getColor() {return this.color;}}
int getColor() {return this.color;}}
class Automobile {
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

19. Motivating Example Revisited
Language Enum
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN};
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red by default */
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public Color getColor() {return this.color;}}
int getColor() {return this.color;}}
class Automobile {
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

20. Motivating Example Revisited
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN};
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red by default */
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public Color getColor() {return this.color;}}
int getColor() {return this.color;}}
class Automobile {
class Automobile {
class Automobile {
Type Safety
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

21. Motivating Example Revisited
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN}; Singletons in initially red by default */
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red default */
/* Current color of the traffic signal,
colorOrder
private ColorNatural = =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public Color getColor() {return this.color;}}
int getColor() {return this.color;}}
class Automobile {
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

22. Motivating Example Revisited
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN};
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red by default */
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return Prefixed
public Color getColor() {return this.color;}}
int getColor() {return this.color;}} this.color;}}
class Automobile {
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

23. Motivating Example Revisited
Supports
Separate
Compilation
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN};
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red by default */
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public Color getColor() {return this.color;}}
int getColor() {return this.color;}}
class Automobile {
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

24. Motivating Example Revisited
class TrafficSignal {{
TrafficSignal
class TrafficSignal {
public enum Color {RED, RED = 0;
public static final int
public enum Color {RED,
YELLOW,
public static final int YELLOW = 1;
YELLOW,
GREEN};
public static final int GREEN = 2;
GREEN};
/∗ Current color of the traffic signal, initially red byby default ∗/
/* Current color of the traffic signal, initially red by default */
/* Current color of the traffic signal, initially red default */
private Color color= =RED;
private Color color = Color.RED;
private int color Color.RED;
/∗ Accessor for the light’s current color */∗/
/* Accessor for the light’s current color */
/* Accessor for the light’s current color
public Color getColor(){return this.color;}}
public Color getColor() {return this.color;}}
int getColor() {return this.color;}}
class Automobile {
class Automobile {
class Automobile {
private enum Action {IDLE,IDLE = 0;
private enum Action {IDLE,
private static final int
INCREASE_SPEED,
INCREASE_SPEED,
private static final int INCREASE_SPEED = 1;
DECREASE_SPEED,
DECREASE_SPEED,
private static final int DECREASE_SPEED = 2;
STOP};
STOP}; static final int STOP = 3;
private static final int MAX_SPEED = 140;
private

25. α '%2"%,&)/ !)&-/ 1)!0#-
αctxt 30"+$5+ "$ 40"+0 α 1%. Enumerization Approach
#++(2
!"#$%& '( !)%*+,"-* .)/+/").(
function E numer iz able(C )P)
.',/&4$'& Enumerize(F,
1: >A W ← C /* seed the worklist with the input constants */
R ← Enumerizable(F )
2: QA N ← ∅ /* the non-enumerizable set ∩ Consistent(R) */
R ← U nique(R) ∩ Distinct(R) list, initially empty
3: GAfor all c T ∈ R 4,
5,' *22 ∈ C do
T ransf orm(T )
4: RA MakeSet(c) /* init the union-find data structure */
?A &#4 5,'
5: end for
6: while W = ∅ do
!"#$%& 0( 1)23,&4&, &.$*&%"5+/"). +,#)%"/6*(
7: /* remove an element from the worklist */
2)9%+!#2"$37 e M)W
8: α ← e | ∈ %&*# %**(1) !0%! 4) %2) %,&) !# *!%!"+%
W ← W {α}
"-)$!"9. %&& 2)9)2)$+)* !# +%$-"-%!) !)&-* %$- !2%$*"!"')&. -
9:
6)$-)$! 62#32%1 Contexts(α, P) do
10: for all αctxt ∈ )$!"!")*7 O0"* %**(16!"#$ +#(&- ,) "$'%
¬isEnumerizableContext (α, αctxt ) then
-%!)-if!02#(30 !0) (*) #9 2)")+!"#$ %$- +(*!#1 +&%** &#%-)
11:

26. α '%2"%,&)/ !)&-/ 1)!0#-
αctxt 30"+$5+ "$ 40"+0 α 1%. Enumerization Approach
#++(2
!"#$%& '( !)%*+,"-* .)/+/").(
Subset of static
function E numer iz able(C )P)
.',/&4$'& Enumerize(F,
final fields
1: >A W ← C /* seed the worklist with the input constants */
R ← Enumerizable(F )
2: QA N ← ∅ /* the non-enumerizable set ∩ Consistent(R) */
R ← U nique(R) ∩ Distinct(R) list, initially empty
3: GAfor all c T ∈ R 4,
5,' *22 ∈ C do
T ransf orm(T )
4: RA MakeSet(c) /* init the union-find data structure */
?A &#4 5,'
5: end for
6: while W = ∅ do
!"#$%& 0( 1)23,&4&, &.$*&%"5+/"). +,#)%"/6*(
7: /* remove an element from the worklist */
2)9%+!#2"$37 e M)W
8: α ← e | ∈ %&*# %**(1) !0%! 4) %2) %,&) !# *!%!"+%
W ← W {α}
"-)$!"9. %&& 2)9)2)$+)* !# +%$-"-%!) !)&-* %$- !2%$*"!"')&. -
9:
6)$-)$! 62#32%1 Contexts(α, P) do
10: for all αctxt ∈ )$!"!")*7 O0"* %**(16!"#$ +#(&- ,) "$'%
¬isEnumerizableContext (α, αctxt ) then
-%!)-if!02#(30 !0) (*) #9 2)")+!"#$ %$- +(*!#1 +&%** &#%-)
11:

27. α '%2"%,&)/ !)&-/ 1)!0#-
αctxt 30"+$5+ "$ 40"+0 α 1%. Enumerization Approach
#++(2
!"#$%& '( !)%*+,"-* .)/+/").(
function E numer iz able(C )P) Abstract Syntax Tree (AST)
.',/&4$'& Enumerize(F,
1: >A W ← C /* seed the worklist with the input constants */
R ← Enumerizable(F )
2: QA N ← ∅ /* the non-enumerizable set ∩ Consistent(R) */
R ← U nique(R) ∩ Distinct(R) list, initially empty
3: GAfor all c T ∈ R 4,
5,' *22 ∈ C do
T ransf orm(T )
4: RA MakeSet(c) /* init the union-find data structure */
?A &#4 5,'
5: end for
6: while W = ∅ do
!"#$%& 0( 1)23,&4&, &.$*&%"5+/"). +,#)%"/6*(
7: /* remove an element from the worklist */
2)9%+!#2"$37 e M)W
8: α ← e | ∈ %&*# %**(1) !0%! 4) %2) %,&) !# *!%!"+%
W ← W {α}
"-)$!"9. %&& 2)9)2)$+)* !# +%$-"-%!) !)&-* %$- !2%$*"!"')&. -
9:
6)$-)$! 62#32%1 Contexts(α, P) do
10: for all αctxt ∈ )$!"!")*7 O0"* %**(16!"#$ +#(&- ,) "$'%
¬isEnumerizableContext (α, αctxt ) then
-%!)-if!02#(30 !0) (*) #9 2)")+!"#$ %$- +(*!#1 +&%** &#%-)
11:

28. α '%2"%,&)/ !)&-/ 1)!0#-
αctxt 30"+$5+ "$ 40"+0 α 1%. Enumerization Approach
#++(2
!"#$%& '( !)%*+,"-* .)/+/").(
function E numer iz able(C )P)
.',/&4$'& Enumerize(F,
Output: C /* seed the worklist with the input constants */
1: >A W ← Enumerizable(F )
R←
2: QA N ← ∅ /* the non-enumerizable set ∩ Consistent(R) */
R ← U nique(R) ∩ Distinct(R) list, initially empty
3: GAfor all c T ∈ R 4,
5,' *22 ∈ C do
T ransf orm(T )
4: RA MakeSet(c) /* init the union-find data structure */
?A &#4 5,'
5: end for
6: while W = ∅ do
!"#$%& 0( 1)23,&4&, &.$*&%"5+/"). +,#)%"/6*(
7: /* remove an element from the worklist */
2)9%+!#2"$37 e M)W
8: α ← e | ∈ %&*# %**(1) !0%! 4) %2) %,&) !# *!%!"+%
W ← W {α}
"-)$!"9. %&& 2)9)2)$+)* !# +%$-"-%!) !)&-* %$- !2%$*"!"')&. -
9:
6)$-)$! 62#32%1 Contexts(α, P) do
10: for all αctxt ∈ )$!"!")*7 O0"* %**(16!"#$ +#(&- ,) "$'%
¬isEnumerizableContext (α, αctxt ) then
-%!)-if!02#(30 !0) (*) #9 2)")+!"#$ %$- +(*!#1 +&%** &#%-)
11:

29. α '%2"%,&)/ !)&-/ 1)!0#-
αctxt 30"+$5+ "$ 40"+0 α 1%. Enumerization Approach
#++(2
!"#$%& '( !)%*+,"-* .)/+/").(
function E numer iz able(C )P)
.',/&4$'& Enumerize(F,
Output: C /* seed the worklist with the input constants */
1: >A W ← Enumerizable(F )
R←
•2: QA NR← ∅U nique(R) ∩ Distinct(R) ∩ Consistent(R) */
Partitioning of program entities: list, initially empty
← /* the non-enumerizable set
3: GAfor all c T ∈ R 4,
5,' *22 ∈ C do
• Fields
T ransf orm(T )
4: RA MakeSet(c) /* init the union-find data structure */
5:
• end for declarations (return types)
?A Method
&#4 5,'
6:• while W = ∅ do (including formal parameters)
Local variables
!"#$%& 0( 1)23,&4&, &.$*&%"5+/"). +,#)%"/6*(
7: /* remove an element from the worklist */
2)9%+!#2"$37 e M)W
8: α ← e | ∈ %&*# %**(1) !0%! 4) %2) %,&) !# *!%!"+%
W ← W {α}
"-)$!"9. %&& 2)9)2)$+)* !# +%$-"-%!) !)&-* %$- !2%$*"!"')&. -
9:
6)$-)$! 62#32%1 Contexts(α, P) do
10: for all αctxt ∈ )$!"!")*7 O0"* %**(16!"#$ +#(&- ,) "$'%
¬isEnumerizableContext (α, αctxt ) then
-%!)-if!02#(30 !0) (*) #9 2)")+!"#$ %$- +(*!#1 +&%** &#%-)
11:

30. α '%2"%,&)/ !)&-/ 1)!0#-
αctxt 30"+$5+ "$ 40"+0 α 1%. Enumerization Approach
#++(2
!"#$%& '( !)%*+,"-* .)/+/").(
function E numer iz able(C )P)
.',/&4$'& Enumerize(F,
Output: C /* seed the worklist with the input constants */
1: >A W ← Enumerizable(F )
R←
•2: QA NR← ∅U nique(R) ∩ Distinct(R) ∩ Consistent(R) */
Partitioning of program entities: list, initially empty
← /* the non-enumerizable set
3: GAfor all c T ∈ R 4,
5,' *22 ∈ C do
• Fields
T ransf orm(T )
4: RA MakeSet(c) /* init the union-find data structure */
5:
• end for declarations (return types)
?A Method
&#4 5,'
6:• while W = ∅ do (including formal parameters)
Local variables
!"#$%& 0( 1)23,&4&, &.$*&%"5+/"). +,#)%"/6*(
/* remove an element from the worklist */
• Each partition contains elements that:
7:
2)9%+!#2"$37 e M)W
8: α ← e | ∈ %&*# %**(1) !0%! 4) %2) %,&) !# *!%!"+%
• Transitively type-dependent upon one another
W ← W {α}
"-)$!"9. %&& 2)9)2)$+)* !# +%$-"-%!) !)&-* %$- !2%$*"!"')&. -
9:
10:• Are all αctxt ∈ Contexts(α, P) do
6)$-)$!safe for enum type transformation +#(&- ,) "$'%
for 62#32%1 )$!"!")*7 O0"* %**(16!"#$
¬isEnumerizableContext (α, αctxt ) then
-%!)-if!02#(30 !0) (*) #9 2)")+!"#$ %$- +(*!#1 +&%** &#%-)
11:

31. Features

32. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.

33. Features
Math.PI
• Infers which static final fields are being used as
enums and which are being used as named constants.

34. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.

35. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values. short,
bool, char, etc.

36. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.

37. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
Uses CHA to
preserve
polymorphism

38. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
• Infers minimal types such that changing one constant
requires changing all constants in the set.

39. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
• Infers minimal types such that changing one constant
requires changing all constants in the set.
Correctly
partitions all input
constants

40. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
• Infers minimal types such that changing one constant
requires changing all constants in the set.
• Preserves semantics by considering intricacies of the
Java language specification and primitive to reference
type conversion.

41. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
• Infers minimal types such that changing one constant
requires changing all constants in the set.
• Preserves semantics by considering intricacies of the
Java language specification and primitive to reference
type conversion.
• Converts primitive operations to method calls.

42. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
• Infers minimal types such that changing one constant
requires changing all constants in the set.
• Preserves semantics by considering intricacies of the
Java language specification and primitive to reference
type conversion.
• Converts primitive operations to method calls.
• Preserves natural ordering.

43. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
• Infers minimal types such that changing one constant
requires changing all constants in the set.
• Preserves semantics by considering intricacies of the
Java language specification and primitive to reference
type conversion.
For comparison
• Converts primitive operations to method calls.
preservation
• Preserves natural ordering.

44. Features
• Infers which static final fields are being used as
enums and which are being used as named constants.
• Works with all primitive values.
• Transformation is fully automated.
• Infers minimal typestime and piece of one constant
Saves such that changing
requires changing all constants in the set.
mind!
• Preserves semantics by considering intricacies of the
Java language specification and primitive to reference
type conversion.
• Converts primitive operations to method calls.
• Preserves natural ordering.

45. Current Limitations

46. Current Limitations
• Still in research prototype stage:

47. Current Limitations
• Still in research prototype stage:
• UI allows for only one enum types creation per
invocation.

48. Current Limitations
• Still in research prototype stage:
• UI allows for only one enum types creation per
invocation.
• UI does not allow user to split constants into smaller
enum types.

49. Current Limitations
• Still in research prototype stage:
• UI allows for only one enum types creation per
invocation.
• UI does not allow user to split constants into smaller
enum types.
• No renaming of constants.

50. Current Limitations
• Still in research prototype stage:
• UI allows for only one enum types creation per
invocation.
• UI does not allow user to split constants into smaller
enum types.
• No renaming of constants.
• Enum type name inference only based on longest
common prefix.

51. Current Limitations
• Still in research prototype stage:
• UI allows for only one enum types creation per
invocation.
• COLOR_RED,
UI does not allow user to split constants into smaller
COLOR_GREEN, ...results
enum types.
in enum Color
• No renaming of constants.
• Enum type name inference only based on longest
common prefix.

52. Current Limitations
• Still in research prototype stage:
• UI allows for only one enum types creation per
invocation.
• UI does not allow user to split constants into smaller
enum types.
• No renaming of constants.
• Enum type name inference only based on longest
common prefix.
• Limited undo support.

53. Resources

54. Resources
• Prototype available at http://code.google.com/p/
constants-to-enum-eclipse-plugin/

55. Resources
• Prototype available at http://code.google.com/p/
constants-to-enum-eclipse-plugin/
• Raffi Khatchadourian, Jason Sawin, and Atanas
Rountev. Automated refactoring of legacy Java
software to enumerated types. In Proceedings of
the 23rd International Conference on Software
Maintenance (ICSM ’07), pages 224–233, Paris,
France, October 2007. IEEE.