[英]The easiest way to achieve a responsive orientation enum? java
我將以“最清晰”的方式快速展示我想要實現的目標:
public enum Orientation {
NORTH, WEST, SOUTH, EAST }
public enum Turn {
LEFT, RIGHT }
因此,我希望這兩個枚舉能夠安全有效地根據移動查找更改的方向:
Orientation orient = Orientation.NORTH;
// orient points to NORTH now
orient = orient.turn(Turn.LEFT);
// orient points to WEST now
我嘗試實現這一目標的第一種方法是創建一個地圖:
EnumMap<Orientation, EnumMap<Turn, Orientation>>
並靜態映射所有方向,但這是一大塊map.get.put.get ....並且可能有點過量,導致這種期望的效果:
directionMap.get(NORTH).get(LEFT)
// the value would then be WEST
我接下來的方式是通過Compass類將所有方向鏈接成一個圓圈。像LinkedCircuitList一樣...... < - > NORTH < - > EAST < - > SOUTH < - > WEST < - > NORTH < - >。 ..因此Compass可以有一個靜態函數,可以調用該鏈表的任何成員並向左或向右移動,從而導致方向的正確更改。 但是代碼並沒有按照我想要的方式運行。
所以我的問題到底是什么,有沒有人有這種代碼的經驗,或者知道如何以一種美好的方式實現理想的結果?
我認為地圖解決方案沒有錯。 如果你想要更簡潔的東西:
public enum Orientation {
NORTH, EAST, SOUTH, WEST;
private static Orientation[] vals = values();
Orientation turnTo(Turn t) {
return vals[(4 + this.ordinal() + (t == Turn.RIGHT ? 1 : -1)) % 4];
}
}
然而,這不太干凈和可維護(如果有人改變了枚舉的順序,它會破裂)。
一點點清潔(但不太明確):
public enum Orientation {
NORTH(0), EAST(1), SOUTH(2), WEST(3);
private final int p;
Orientation(int p) {
this.p = p;
}
private static Orientation[] vals = new Orientation[4];
static {
for( Orientation o : Orientation.values() )
vals[o.p] = o;
}
Orientation turnTo(Turn t) {
return vals[(4 + this.p + (t == Turn.RIGHT ? 1 : -1)) % 4];
}
}
欺騙java接受這個的另一種方法是使用方法而不是字段:
enum Orientation {
NORTH {
Orientation left(){return WEST;}
Orientation right(){return EAST;}
},
EAST {
Orientation left(){return NORTH;}
Orientation right(){return SOUTH;}
},
SOUTH {
Orientation left(){return EAST;}
Orientation right(){return WEST;}
},
WEST {
Orientation left(){return SOUTH;}
Orientation right(){return NORTH;}
};
abstract Orientation left();
abstract Orientation right();
public Orientation turn(Turn where){
return where == Turn.LEFT ? this.left() : this.right();
}
}
如果你願意,你可以保存自己的turn()
並只寫像Orientation.North.left()
這樣的東西。 為您提供非常簡潔的語法。
我認為你對循環列表的想法非常好:
public enum Turn {
LEFT(-1), RIGHT(1);
private final int offset;
private Turn(int offset) {
this.offset = offset;
}
public int offset() {
return this.offset;
}
}
public enum Orientation {
NORTH, EAST, SOUTH, WEST;
private static final List<Orientation> orientations =
Arrays.asList(NORTH, EAST, SOUTH, WEST); // to not depend on ordinal
public Orientation turn(Turn to) {
int size = orientations.size();
int myIndex = orientations.indexOf(this);
int remainder = (myIndex + to.offset()) % size;
int index = remainder < 0 ? size + remainder : remainder;
return orientations.get(index);
}
}
這似乎是非常可擴展的,即HARD_LEFT將具有-2
偏移,並且循環的方向列表應該從左到右排序。
不使用序數,易於理解:
public enum Orientation { NORTH, WEST, EAST, SOUTH;
static {
NORTH.left = WEST;
NORTH.right = EAST;
WEST.left = SOUTH;
WEST.right = NORTH;
EAST.left = NORTH;
EAST.right = SOUTH;
SOUTH.left = EAST;
SOUTH.right = WEST;
}
private Orientation left;
private Orientation right;
public Orientation turnTo(Turn t) { return t == Turn.LEFT ? left : right; }
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.