Log4J 1.2文档中的奇怪演员

Question

I was looking through Log4J docs and stumbled at the following in the description of Logger#setLevel() (inherited from Category ) method:

If you are passing any of Level.DEBUG , Level.INFO , Level.WARN , Level.ERROR , Level.FATAL as a parameter, you need to case them as Level . As in

 logger.setLevel((Level) Level.DEBUG); 

Is there any reason behind such requirement?

Am I missing something here?

Answer 1

This seems like a documentation error that was introduced when Category.setPriority() was deprecated and Category.setLevel() was added in the 1.2 version.

This is how the setPriority method originally looked like in jakarta-log4j-1.1.3 :

/**
 Set the priority of this Category.
 <p>Null values are admitted.
*/
public void setPriority(Priority priority) {
    this.priority = priority;
}

Looking at the source for setPriority in log4j-1.2.17 , we can see that when the method was deprecated, a narrowing cast to Level was added:

/**
 Set the level of this Category.
 <p>Null values are admitted.
 @deprecated Please use {@link #setLevel} instead.
*/
public void setPriority(Priority priority) {
   this.level = (Level) priority;
}

So, it seems like an implementation detail of setPriority somehow slipped into the JavaDocs of the new setLevel method. Obviously, the documentation makes no sense as the cast is not required.