Enum of directions with opposites

Clash Royale CLAN TAG#URR8PPP

up vote
6
down vote

favorite

I'm currently working on a Dungeon game project which is composed of multiples rooms connected to each other.
Depending on the room you're in you can go to rooms next to yours by picking directions (North, South, East, West)
I've represented the directions with an Enum class and I'm looking for a way to implements that North is the opposite of South, East for West (and so on ...) for the sake of creating the layout of all the rooms in the final form of the game

Here is my Enum class :

public enum Direction 
 NORTH,
 EAST,
 SOUTH,
 WEST;

 public Direction getOppositeDirection() 
 return Direction.values()[(this.ordinal()+2)%4];
 

The problem is that currently the method is not very safe, any change in the order of declarations in the direction will break the method, any suggestions on how to do this in a better way ? Thanks !

java enums

share

asked 55 mins ago

Rémy.W

685

add a comment | 

up vote
6
down vote

favorite

I'm currently working on a Dungeon game project which is composed of multiples rooms connected to each other.
Depending on the room you're in you can go to rooms next to yours by picking directions (North, South, East, West)
I've represented the directions with an Enum class and I'm looking for a way to implements that North is the opposite of South, East for West (and so on ...) for the sake of creating the layout of all the rooms in the final form of the game

Here is my Enum class :

public enum Direction 
 NORTH,
 EAST,
 SOUTH,
 WEST;

 public Direction getOppositeDirection() 
 return Direction.values()[(this.ordinal()+2)%4];
 

The problem is that currently the method is not very safe, any change in the order of declarations in the direction will break the method, any suggestions on how to do this in a better way ? Thanks !

java enums

share

asked 55 mins ago

Rémy.W

685

add a comment | 

up vote
6
down vote

favorite

up vote
6
down vote

favorite

I'm currently working on a Dungeon game project which is composed of multiples rooms connected to each other.
Depending on the room you're in you can go to rooms next to yours by picking directions (North, South, East, West)
I've represented the directions with an Enum class and I'm looking for a way to implements that North is the opposite of South, East for West (and so on ...) for the sake of creating the layout of all the rooms in the final form of the game

Here is my Enum class :

public enum Direction 
 NORTH,
 EAST,
 SOUTH,
 WEST;

 public Direction getOppositeDirection() 
 return Direction.values()[(this.ordinal()+2)%4];
 

The problem is that currently the method is not very safe, any change in the order of declarations in the direction will break the method, any suggestions on how to do this in a better way ? Thanks !

java enums

share

asked 55 mins ago

Rémy.W

685

I'm currently working on a Dungeon game project which is composed of multiples rooms connected to each other.
Depending on the room you're in you can go to rooms next to yours by picking directions (North, South, East, West)
I've represented the directions with an Enum class and I'm looking for a way to implements that North is the opposite of South, East for West (and so on ...) for the sake of creating the layout of all the rooms in the final form of the game

Here is my Enum class :

public enum Direction 
 NORTH,
 EAST,
 SOUTH,
 WEST;

 public Direction getOppositeDirection() 
 return Direction.values()[(this.ordinal()+2)%4];
 

The problem is that currently the method is not very safe, any change in the order of declarations in the direction will break the method, any suggestions on how to do this in a better way ? Thanks !

java enums

java enums

share

asked 55 mins ago

Rémy.W

685

share

asked 55 mins ago

Rémy.W

685

share

share

asked 55 mins ago

Rémy.W

685

asked 55 mins ago

Rémy.W

685

asked 55 mins ago

Rémy.W

685

685

add a comment | 

add a comment | 

3 Answers
3

active

oldest

votes

up vote
6
down vote



accepted

You could make the method abstract, and implement it for each constant.

enum Direction 
 NORTH() 
 public Direction getOppositeDirection() 
 return SOUTH;
 
 ,
 EAST() 
 public Direction getOppositeDirection() 
 return WEST;
 
 ,
 SOUTH() 
 public Direction getOppositeDirection() 
 return NORTH;
 
 ,
 WEST() 
 public Direction getOppositeDirection() 
 return EAST;
 
 ;

 public abstract Direction getOppositeDirection();

It's a bit wordy, though.

The next method is shorter but more difficult to read.

enum Direction 
 NORTH, EAST, SOUTH, WEST;

 static 
 (SOUTH.oppositeDirection = NORTH).oppositeDirection = SOUTH;
 (WEST.oppositeDirection = EAST).oppositeDirection = WEST;
 

 private Direction oppositeDirection;

 public Direction getOppositeDirection() 
 return oppositeDirection;
 

share|improve this answer

edited 13 mins ago

answered 47 mins ago

Andrew Tobilko

22.4k83876

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Opposite of North is South :)
  – Nicholas K
  41 mins ago
  

  
  
  
  

add a comment | 

up vote
2
down vote

You may also want to look in lambda:

public enum Direction 
 NORTH(() -> SOUTH),
 EAST(() -> WEST),
 SOUTH(() -> NORTH),
 WEST(() -> EAST);

 private final Supplier<Direction> direction;

 private Direction(Supplier<Direction> direction) 
 this.direction = direction;
 

 public final Direction getOppositeDirection() 
 return direction.get();
 

This does the same than having abstract method, but is more concise: you read directly what is the opposite direction instead of having the verbose method declaration (it is another matter if you need to also add other methods).

Also, it will not create pseudo class for each enums constant (eg: Direction$1, Direction$2, ...) because there is no need to.

share|improve this answer

answered 27 mins ago

NoDataFound

5,1311539

• 
  
  
  

  
  

  
  
  
  
  
  

  
  I thought about it, but it shouldn't compile because there are 2 illegal forward references here.
  – Andrew Tobilko
  26 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There are no forward reference: it would make an error if I was passing the field directly in the constructor, but that is not the case here. The lambda is not evaluated before getOppositeDirection get called.
  – NoDataFound
  2 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

Since you have only 4 values, I feel it would be better to hard-code the opposites:

public Direction getOppositeDirection() 
 switch(this.name())
 case "NORTH":
 return SOUTH;
 case "SOUTH":
 return NORTH;
 case "EAST":
 return WEST;
 case "WEST":
 return EAST;
 

share|improve this answer

edited 44 mins ago

answered 45 mins ago

Susmit Agrawal

882411

• 
  
  
  

  
  

  
  
  
  
  
  

  
  If you have return then break is duplicate
  – lucumt
  44 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Why would you switch on a String (the name) when you can just switch on this and do it in a safe manner?
  – Erwin Bolwidt
  43 mins ago
  

  
  
  
  

add a comment | 

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3 Answers
3

active

oldest

votes

3 Answers
3

active

oldest

votes

active

oldest

votes

active

oldest

votes

up vote
6
down vote



accepted

You could make the method abstract, and implement it for each constant.

enum Direction 
 NORTH() 
 public Direction getOppositeDirection() 
 return SOUTH;
 
 ,
 EAST() 
 public Direction getOppositeDirection() 
 return WEST;
 
 ,
 SOUTH() 
 public Direction getOppositeDirection() 
 return NORTH;
 
 ,
 WEST() 
 public Direction getOppositeDirection() 
 return EAST;
 
 ;

 public abstract Direction getOppositeDirection();

It's a bit wordy, though.

The next method is shorter but more difficult to read.

enum Direction 
 NORTH, EAST, SOUTH, WEST;

 static 
 (SOUTH.oppositeDirection = NORTH).oppositeDirection = SOUTH;
 (WEST.oppositeDirection = EAST).oppositeDirection = WEST;
 

 private Direction oppositeDirection;

 public Direction getOppositeDirection() 
 return oppositeDirection;
 

share|improve this answer

edited 13 mins ago

answered 47 mins ago

Andrew Tobilko

22.4k83876

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Opposite of North is South :)
  – Nicholas K
  41 mins ago
  

  
  
  
  

add a comment | 

up vote
6
down vote



accepted

You could make the method abstract, and implement it for each constant.

enum Direction 
 NORTH() 
 public Direction getOppositeDirection() 
 return SOUTH;
 
 ,
 EAST() 
 public Direction getOppositeDirection() 
 return WEST;
 
 ,
 SOUTH() 
 public Direction getOppositeDirection() 
 return NORTH;
 
 ,
 WEST() 
 public Direction getOppositeDirection() 
 return EAST;
 
 ;

 public abstract Direction getOppositeDirection();

It's a bit wordy, though.

The next method is shorter but more difficult to read.

enum Direction 
 NORTH, EAST, SOUTH, WEST;

 static 
 (SOUTH.oppositeDirection = NORTH).oppositeDirection = SOUTH;
 (WEST.oppositeDirection = EAST).oppositeDirection = WEST;
 

 private Direction oppositeDirection;

 public Direction getOppositeDirection() 
 return oppositeDirection;
 

share|improve this answer

edited 13 mins ago

answered 47 mins ago

Andrew Tobilko

22.4k83876

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Opposite of North is South :)
  – Nicholas K
  41 mins ago
  

  
  
  
  

add a comment | 

up vote
6
down vote



accepted

up vote
6
down vote



accepted

You could make the method abstract, and implement it for each constant.

enum Direction 
 NORTH() 
 public Direction getOppositeDirection() 
 return SOUTH;
 
 ,
 EAST() 
 public Direction getOppositeDirection() 
 return WEST;
 
 ,
 SOUTH() 
 public Direction getOppositeDirection() 
 return NORTH;
 
 ,
 WEST() 
 public Direction getOppositeDirection() 
 return EAST;
 
 ;

 public abstract Direction getOppositeDirection();

It's a bit wordy, though.

The next method is shorter but more difficult to read.

enum Direction 
 NORTH, EAST, SOUTH, WEST;

 static 
 (SOUTH.oppositeDirection = NORTH).oppositeDirection = SOUTH;
 (WEST.oppositeDirection = EAST).oppositeDirection = WEST;
 

 private Direction oppositeDirection;

 public Direction getOppositeDirection() 
 return oppositeDirection;
 

share|improve this answer

edited 13 mins ago

answered 47 mins ago

Andrew Tobilko

22.4k83876

You could make the method abstract, and implement it for each constant.

enum Direction 
 NORTH() 
 public Direction getOppositeDirection() 
 return SOUTH;
 
 ,
 EAST() 
 public Direction getOppositeDirection() 
 return WEST;
 
 ,
 SOUTH() 
 public Direction getOppositeDirection() 
 return NORTH;
 
 ,
 WEST() 
 public Direction getOppositeDirection() 
 return EAST;
 
 ;

 public abstract Direction getOppositeDirection();

It's a bit wordy, though.

The next method is shorter but more difficult to read.

enum Direction 
 NORTH, EAST, SOUTH, WEST;

 static 
 (SOUTH.oppositeDirection = NORTH).oppositeDirection = SOUTH;
 (WEST.oppositeDirection = EAST).oppositeDirection = WEST;
 

 private Direction oppositeDirection;

 public Direction getOppositeDirection() 
 return oppositeDirection;
 

share|improve this answer

edited 13 mins ago

answered 47 mins ago

Andrew Tobilko

22.4k83876

share|improve this answer

share|improve this answer

edited 13 mins ago

edited 13 mins ago

edited 13 mins ago

answered 47 mins ago

Andrew Tobilko

22.4k83876

answered 47 mins ago

Andrew Tobilko

22.4k83876

answered 47 mins ago

Andrew Tobilko

22.4k83876

22.4k83876

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Opposite of North is South :)
  – Nicholas K
  41 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  Opposite of North is South :)
  – Nicholas K
  41 mins ago
  

  
  
  
  

2

2

Opposite of North is South :)
– Nicholas K
41 mins ago

Opposite of North is South :)
– Nicholas K
41 mins ago

add a comment | 

up vote
2
down vote

You may also want to look in lambda:

public enum Direction 
 NORTH(() -> SOUTH),
 EAST(() -> WEST),
 SOUTH(() -> NORTH),
 WEST(() -> EAST);

 private final Supplier<Direction> direction;

 private Direction(Supplier<Direction> direction) 
 this.direction = direction;
 

 public final Direction getOppositeDirection() 
 return direction.get();
 

This does the same than having abstract method, but is more concise: you read directly what is the opposite direction instead of having the verbose method declaration (it is another matter if you need to also add other methods).

Also, it will not create pseudo class for each enums constant (eg: Direction$1, Direction$2, ...) because there is no need to.

share|improve this answer

answered 27 mins ago

NoDataFound

5,1311539

• 
  
  
  

  
  

  
  
  
  
  
  

  
  I thought about it, but it shouldn't compile because there are 2 illegal forward references here.
  – Andrew Tobilko
  26 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There are no forward reference: it would make an error if I was passing the field directly in the constructor, but that is not the case here. The lambda is not evaluated before getOppositeDirection get called.
  – NoDataFound
  2 mins ago
  

  
  
  
  

add a comment | 

up vote
2
down vote

You may also want to look in lambda:

public enum Direction 
 NORTH(() -> SOUTH),
 EAST(() -> WEST),
 SOUTH(() -> NORTH),
 WEST(() -> EAST);

 private final Supplier<Direction> direction;

 private Direction(Supplier<Direction> direction) 
 this.direction = direction;
 

 public final Direction getOppositeDirection() 
 return direction.get();
 

This does the same than having abstract method, but is more concise: you read directly what is the opposite direction instead of having the verbose method declaration (it is another matter if you need to also add other methods).

Also, it will not create pseudo class for each enums constant (eg: Direction$1, Direction$2, ...) because there is no need to.

share|improve this answer

answered 27 mins ago

NoDataFound

5,1311539

• 
  
  
  

  
  

  
  
  
  
  
  

  
  I thought about it, but it shouldn't compile because there are 2 illegal forward references here.
  – Andrew Tobilko
  26 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There are no forward reference: it would make an error if I was passing the field directly in the constructor, but that is not the case here. The lambda is not evaluated before getOppositeDirection get called.
  – NoDataFound
  2 mins ago
  

  
  
  
  

add a comment | 

up vote
2
down vote

up vote
2
down vote

You may also want to look in lambda:

public enum Direction 
 NORTH(() -> SOUTH),
 EAST(() -> WEST),
 SOUTH(() -> NORTH),
 WEST(() -> EAST);

 private final Supplier<Direction> direction;

 private Direction(Supplier<Direction> direction) 
 this.direction = direction;
 

 public final Direction getOppositeDirection() 
 return direction.get();
 

This does the same than having abstract method, but is more concise: you read directly what is the opposite direction instead of having the verbose method declaration (it is another matter if you need to also add other methods).

Also, it will not create pseudo class for each enums constant (eg: Direction$1, Direction$2, ...) because there is no need to.

share|improve this answer

answered 27 mins ago

NoDataFound

5,1311539

You may also want to look in lambda:

public enum Direction 
 NORTH(() -> SOUTH),
 EAST(() -> WEST),
 SOUTH(() -> NORTH),
 WEST(() -> EAST);

 private final Supplier<Direction> direction;

 private Direction(Supplier<Direction> direction) 
 this.direction = direction;
 

 public final Direction getOppositeDirection() 
 return direction.get();
 

This does the same than having abstract method, but is more concise: you read directly what is the opposite direction instead of having the verbose method declaration (it is another matter if you need to also add other methods).

Also, it will not create pseudo class for each enums constant (eg: Direction$1, Direction$2, ...) because there is no need to.

share|improve this answer

answered 27 mins ago

NoDataFound

5,1311539

share|improve this answer

share|improve this answer

answered 27 mins ago

NoDataFound

5,1311539

answered 27 mins ago

NoDataFound

5,1311539

answered 27 mins ago

NoDataFound

5,1311539

5,1311539

• 
  
  
  

  
  

  
  
  
  
  
  

  
  I thought about it, but it shouldn't compile because there are 2 illegal forward references here.
  – Andrew Tobilko
  26 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There are no forward reference: it would make an error if I was passing the field directly in the constructor, but that is not the case here. The lambda is not evaluated before getOppositeDirection get called.
  – NoDataFound
  2 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  I thought about it, but it shouldn't compile because there are 2 illegal forward references here.
  – Andrew Tobilko
  26 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There are no forward reference: it would make an error if I was passing the field directly in the constructor, but that is not the case here. The lambda is not evaluated before getOppositeDirection get called.
  – NoDataFound
  2 mins ago
  

  
  
  
  

I thought about it, but it shouldn't compile because there are 2 illegal forward references here.
– Andrew Tobilko
26 mins ago

I thought about it, but it shouldn't compile because there are 2 illegal forward references here.
– Andrew Tobilko
26 mins ago

There are no forward reference: it would make an error if I was passing the field directly in the constructor, but that is not the case here. The lambda is not evaluated before getOppositeDirection get called.
– NoDataFound
2 mins ago

There are no forward reference: it would make an error if I was passing the field directly in the constructor, but that is not the case here. The lambda is not evaluated before getOppositeDirection get called.
– NoDataFound
2 mins ago

add a comment | 

up vote
1
down vote

Since you have only 4 values, I feel it would be better to hard-code the opposites:

public Direction getOppositeDirection() 
 switch(this.name())
 case "NORTH":
 return SOUTH;
 case "SOUTH":
 return NORTH;
 case "EAST":
 return WEST;
 case "WEST":
 return EAST;
 

share|improve this answer

edited 44 mins ago

answered 45 mins ago

Susmit Agrawal

882411

• 
  
  
  

  
  

  
  
  
  
  
  

  
  If you have return then break is duplicate
  – lucumt
  44 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Why would you switch on a String (the name) when you can just switch on this and do it in a safe manner?
  – Erwin Bolwidt
  43 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

Since you have only 4 values, I feel it would be better to hard-code the opposites:

public Direction getOppositeDirection() 
 switch(this.name())
 case "NORTH":
 return SOUTH;
 case "SOUTH":
 return NORTH;
 case "EAST":
 return WEST;
 case "WEST":
 return EAST;
 

share|improve this answer

edited 44 mins ago

answered 45 mins ago

Susmit Agrawal

882411

• 
  
  
  

  
  

  
  
  
  
  
  

  
  If you have return then break is duplicate
  – lucumt
  44 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Why would you switch on a String (the name) when you can just switch on this and do it in a safe manner?
  – Erwin Bolwidt
  43 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

up vote
1
down vote

Since you have only 4 values, I feel it would be better to hard-code the opposites:

public Direction getOppositeDirection() 
 switch(this.name())
 case "NORTH":
 return SOUTH;
 case "SOUTH":
 return NORTH;
 case "EAST":
 return WEST;
 case "WEST":
 return EAST;
 

share|improve this answer

edited 44 mins ago

answered 45 mins ago

Susmit Agrawal

882411

Since you have only 4 values, I feel it would be better to hard-code the opposites:

public Direction getOppositeDirection() 
 switch(this.name())
 case "NORTH":
 return SOUTH;
 case "SOUTH":
 return NORTH;
 case "EAST":
 return WEST;
 case "WEST":
 return EAST;
 

share|improve this answer

edited 44 mins ago

answered 45 mins ago

Susmit Agrawal

882411

share|improve this answer

share|improve this answer

edited 44 mins ago

edited 44 mins ago

edited 44 mins ago

answered 45 mins ago

Susmit Agrawal

882411

answered 45 mins ago

Susmit Agrawal

882411

answered 45 mins ago

Susmit Agrawal

882411

882411

• 
  
  
  

  
  

  
  
  
  
  
  

  
  If you have return then break is duplicate
  – lucumt
  44 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Why would you switch on a String (the name) when you can just switch on this and do it in a safe manner?
  – Erwin Bolwidt
  43 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  If you have return then break is duplicate
  – lucumt
  44 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Why would you switch on a String (the name) when you can just switch on this and do it in a safe manner?
  – Erwin Bolwidt
  43 mins ago
  

  
  
  
  

If you have return then break is duplicate
– lucumt
44 mins ago

If you have return then break is duplicate
– lucumt
44 mins ago

Why would you switch on a String (the name) when you can just switch on this and do it in a safe manner?
– Erwin Bolwidt
43 mins ago

Why would you switch on a String (the name) when you can just switch on this and do it in a safe manner?
– Erwin Bolwidt
43 mins ago

add a comment | 

 

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