如何从枚举构造函数抛出异常？

发布于 2024-09-15 03:46:57 字数 210 浏览 6 评论 0原文

如何从枚举构造函数抛出异常？例如：

public enum RLoader {
  INSTANCE;
  private RLoader() throws IOException {
   ....
  }
}

产生错误

未处理的异常类型 IOException

原文

How can I throw an exception from an enum constructor? eg:

public enum RLoader {
  INSTANCE;
  private RLoader() throws IOException {
   ....
  }
}

produces the error

Unhandled exception type IOException

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遮了一弯 2024-09-22 03:46:57

由于实例是在静态初始化程序中创建的，因此应抛出 ExceptionInInitializerError 。

throw new ExceptionInInitializerError();

Because instances are created in a static initializer, throw an ExceptionInInitializerError instead.

throw new ExceptionInInitializerError();

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我恋#小黄人 2024-09-22 03:46:57

我有一个例子，我想在某些设置类中使用枚举作为键。数据库将存储一个字符串值，允许我们更改枚举常量，而不必更新数据库（我知道有点难看）。我想在枚举的构造函数中抛出一个运行时异常，作为监管字符串参数长度的一种方式，以避免访问数据库，然后在我自己可以轻松检测到它时发生约束冲突。

public enum GlobalSettingKey {
    EXAMPLE("example");

    private String value;

    private GlobalSettingKey(String value) {
        if (value.length() > 200) {
            throw new IllegalArgumentException("you can't do that");
        }
        this.value = value;
    }

    @Override
    public String toString() {
        return value;
    }
}

当我为此创建一个快速测试时，我发现抛出的异常不是我的，而是 ExceptionInInitializerError。

也许这很愚蠢，但我认为对于想要在静态初始化程序中抛出异常来说，这是一个相当有效的场景。

I have a case where I want to use enums as keys in some settings classes. The database will store a string value, allowing us to change the enum constants without having to udpate the database (a bit ugly, I know). I wanted to throw a runtime exception in the enum's constructor as a way to police the length of the string argument to avoid hitting the database and then getting a constraint violation when I could easily detect it myself.

public enum GlobalSettingKey {
    EXAMPLE("example");

    private String value;

    private GlobalSettingKey(String value) {
        if (value.length() > 200) {
            throw new IllegalArgumentException("you can't do that");
        }
        this.value = value;
    }

    @Override
    public String toString() {
        return value;
    }
}

When I created a quick test for this, I found that the exception thrown was not mine, but instead was an ExceptionInInitializerError.

Maybe this is dumb, but I think it's a fairly valid scenario for wanting to throw an exception in a static initializer.

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