Java 我需要检查枚举元素是否进入枚举集
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I need check if enum element is into enum set
提问by Bondezan
I'm new in java. I need check if enum element is into enum set.
我是 Java 新手。我需要检查枚举元素是否进入枚举集。
in Delphi:
在德尔福：
type
TWeekEnum = (weMonday, weTuesday, weWednesday, weThursday, weFriday, weSaturday, weSunday)
TWeekSetEnum = (weSaturday, weSunday)
if (weSunday in (TWeekSetEnum))
...
Java?
爪哇？
回答by Ian McLaird
You can define the enumthis way, and then also create your subsets as static methods on it.
您可以以enum这种方式定义，然后也可以在其上创建您的子集作为静态方法。
public enum TWeekEnum {
weMonday, weTuesday, weWednesday, weThursday, weFriday, weSaturday, weSunday;
public static EnumSet<TWeekEnum> getWeekend() {
return EnumSet.of(weSaturday, weSunday);
}
public static EnumSet<TWeekEnum> getWeekDays() {
return EnumSet.complementOf(getWeekend());
}
}
Then you can check if it contains your selected item like this
然后你可以检查它是否包含你选择的项目
TWeekEnum.getWeekend().contains(TWeekEnum.weTuesday)
回答by bobmarksie
If you prefer the elements to be in the calling code(and not inside the enum) - another solution is to add a normal method named inas follows: -
如果您希望元素位于调用代码中（而不是在枚举中） - 另一种解决方案是添加一个名为in如下的普通方法： -
public enum TWeekEnum {
weMonday, weTuesday, weWednesday, weThursday, weFriday, weSaturday, weSunday;
public boolean in (TWeekEnum ... weekEnum) {
return Arrays.asList(types).contains(this);
}
}
This can be called anywhere in the codebase as follows: -
这可以在代码库中的任何地方调用，如下所示： -
TWeekEnum weekEnum = TWeekEnum.weSaturday; // <---- If set dynamically, check for null
if (weekEnum.in(TWeekEnum.weSaturday, TWeekEnum.weSunday)) {
// do something
}
... this can look nicer (and read better) if enum values statically imported i.e.
...如果枚举值静态导入，这可以看起来更好（并且阅读更好），即
import static com.foo.TWeekEnum.weSaturday;
import static com.foo.TWeekEnum.weSunday;
...
if (weekEnum.in(weSaturday, weSunday)) {
// do something
}
