没有未经检查的警告的通用枚举解析器

Question

如何去掉下面代码中的@SuppressWarnings("unchecked")？

public <T extends Enum<T>> T getEnum( String key, T dflt ) {
   final String value = properties.getProperty( key, dflt.name());
   @SuppressWarnings("unchecked")
   final Class<T> clazz = (Class<T>)dflt.getClass();
   return Enum.valueOf( clazz, value );
}

Answer 1

所有 Enum<E> sub类都有一个 return 其 Class 已正确参数化的方法。

public <T extends Enum<T>> T getEnum(String key, T dflt) {
    final String value = properties.getProperty(key, dflt.name());
    final Class<T> clazz = dflt.getDeclaringClass();
    return Enum.valueOf(clazz, value);
}

编辑：您之前的解决方案是错误的，不仅仅是风格不佳。

public final Class<E> getDeclaringClass()
Returns the Class object corresponding to this enum constant's enum type. Two enum constants e1 and e2 are of the same enum type if and only if e1.getDeclaringClass() == e2.getDeclaringClass(). (The value returned by this method may differ from the one returned by the Object.getClass() method for enum constants with constant-specific class bodies.)

如果传入的 Class 是 "enum constants with constant-specific class bodies" 的 Class，

Enum.valueOf(Class, String) 可能会抱怨。 Class.isEnum() return false 类.

没有未经检查的警告的通用枚举解析器

Generic Enum Parser without unchecked warning

java

generics

enums

warnings