我可以让这个 switch 语句更小吗？最好有 for 循环

如何解决我可以让这个 switch 语句更小吗？最好有 for 循环

有没有办法让它更小，我尝试使用 for 循环，但无法为每个可能的类型创建一个随机实例。

Random randFireworkEffect = new Random(5);
switch(randFireworkEffect.nextInt()) {
    case 0:
        e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.BALL).trail(true).build();
        break;
    case 1:
        e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.BALL_LARGE).trail(true).build();
        break;
    case 2:
         e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.BURST).trail(true).build();
        break;
    case 3:
         e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.CREEPER).trail(true).build();
        break;
    case 4:
         e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.STAR).trail(true).build();
        break;
}

解决方法

你可以使用.values()

Random randFireworkEffect = new Random();
e = FireworkEffect.builder()
        .flicker(true)
        .withColor(c)
        .withFade(c)
        .with(FireworkEffect.Type.values([randFireworkEffect.nextInt(5)])
        .trail(true)
        .build();

,

要做到这一点：

Random randFireworkEffect = new Random(5);
                                switch(randFireworkEffect.nextInt()) {
                                case 0:
                                    e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.BALL).trail(true).build();
                                    break;
                                case 1:
                                    e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.BALL_LARGE).trail(true).build();
                                    break;
                                case 2:
                                     e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.BURST).trail(true).build();
                                    break;
                                case 3:
                                     e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.CREEPER).trail(true).build();
                                    break;
                                case 4:
                                     e = FireworkEffect.builder().flicker(true).withColor(c).withFade(c).with(Type.STAR).trail(true).build();
                                    break;

更短，看看所有这些行之间到底有什么区别，就是类型：

Type[] types = new Type[]{Type.BALL,Type.BALL_LARGE,Type.BURST,Type.CREEPER,Type.STAR};
Random effect = new Random(5);
e = FireworkEffect.builder().flicker(true)
    .withColor(c).withFade(c)
    .with(types[effect.nextInt()])
    .trail(true).build();

是的，您可以将其放入循环中，以设置更多值。

,

有以下最佳做法可以避免出现虚假的 case-statements。首先应该创建一些预定义关系的映射。然后您就可以在运行时从中获取值。

private static final Map<Integer,Type> typeMap = new Hashmap<>();

static {
  typeMap.put(0,Type.BALL);
  typeMap.put(1,Type.BALL_LARGE);
  typeMap.put(2,Type.BURST);
  typeMap.put(3,Type.CREEPER);
  typeMap.put(4,Type.STAR);
}

public FireworkEffect getFireworkEffect() {
   Random randFireworkEffect = new Random(5);
   Type type = typeMap.get(randFireworkEffect);
   return FireworkEffect.builder()
          .flicker(true)
          .withColor(c)
          .withFade(c)
          .with(type)
          .trail(true)
          .build();
}

,

迭代 .values() 不是最优的。最好使用预填充哈希映射

Map<Integer,Type> typeMap = new HashMap<>();
typeMap.put(0,Type.BALL);
typeMap.put(1,Type.BALL_LARGE);
// ... other options

Random randFireworkEffect = new Random(5);
e = FireworkEffect.builder()
        .flicker(true)
        .withColor(c)
        .withFade(c)
        .with(typeMap.get(randFireworkEffect.nextInt()))
        .trail(true)
        .build();