使用枚举的序数值对Java中的数组进行索引是不好的做法吗？ [英] Is it bad practice to use an Enum's ordinal value to index an array in Java?

问题描述

我有两个数组：墙壁和邻居。

  public boolean [] walls = new boolean [ 
 public Cell [] neighbors = new Cell [4]; 
  

我有一个枚举：

 枚举目录
 {
北，
南，
东，
西
} 
  

现在，我想通过他们的方向访问墙壁或邻居，所以我不必传递但是，当我正在阅读Enum.ordinal（）的文档时，它表示，程序员几乎没有使用这种方法，这让我想起了不应该以这种方式使用。

我在想这样做：

 列表<目录> availableDirections = new ArrayList< Dir>（）; 
 for（Dir direction：Dir.values（））
 if（！Neighbors [direction.ordinal（）]。Visited）
 availableDirections.add（direction）; 
  

甚至：

  return Neighbors [Dir.North.ordinal（）]; 
  

我应该恢复为NORTH，SOUTH，EAST，WEST使用静态常量，索引值设置为他们或使用枚举的顺序方法？

解决方案

在一个切入点的问题上，为邻居使用EnumMap可能会更好：

 地图<目录，单元格> neighbors = 
 Collections.synchronizedMap（new EnumMap< Dir，Cell>（Dir.class））; 
 
 neighbours.put（Dir.North，new Cell（））; 
 
 for（Map.Entry< Dir，Cell> neighbor：neighbours.entrySet（））{
 if（neighbour.isVisited（））{...} 
} 
 
等.. 
  

BTW：按照惯例，

 枚举目录{
 NORTH，
 EAST，
 SOUTH，
 WEST 
} 
  

I have two arrays: Walls and Neighbors.

public boolean[] walls = new boolean[4];
public Cell[] neighbors = new Cell[4];

and I have an Enum:

enum Dir
{
    North,
    South,
    East,
    West
}

Now, I would like to be able to access walls or neighbors by their direction, so I don't have to pass around a bunch of magic indexes.

However, when I was reading the documentation for Enum.ordinal() it said that programmers will have almost no use for this method which made me think it shouldn't be used in this way.

I was thinking of doing something like:

    List<Dir> availableDirections = new ArrayList<Dir>();
    for(Dir direction : Dir.values())
        if (!Neighbors[direction.ordinal()].Visited)
            availableDirections.add(direction);

or even:

return Neighbors[Dir.North.ordinal()];

Should I revert to using static constants for NORTH, SOUTH, EAST, WEST with the index value set to them or use an Enum's ordinal method?

解决方案

On a tangential issue, it might be better to use an EnumMap for your neighbours:

Map<Dir, Cell> neighbours = 
    Collections.synchronizedMap(new EnumMap<Dir, Cell>(Dir.class));

neighbours.put(Dir.North, new Cell());

for (Map.Entry<Dir, Cell> neighbour : neighbours.entrySet()) {
    if (neighbour.isVisited()) { ... }
}

etc..

BTW: Enum instances should by convention be all caps,

enum Dir {
    NORTH,
    EAST, 
    SOUTH,
    WEST
}

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