Java: unchecked convert from X to Y / how to implement castornull

I have implemented this function:

static <X,Y> Y castOrNull(X obj) {
  try {
   return (Y)obj;
  }
  catch(ClassCastException e) {
   return null;
  }
 }

This gives me a compiler warning:

Type safety: Unchecked cast from X to Y

I don't understand. Isn't the attempt / capture I made here a check? Can I ignore this warning?

Will my features work as expected? How can I implement it correctly?

I also try to use y to check obj instances, but this doesn't work because of the way Java handles generics

By the way, this function seems very useful to me (making other code cleaner) I wonder if such a function already exists in Java?

An example of how I want to use it:

void removeEmptyRawStrings() {
        for(Iterator<Entity> e = entities.iterator(); e.hasNext();) {
            RawString s = castOrNull(e.next());
            if(s != null && s.content.isEmpty()) e.remove();
        }
    }

This often happens in my code I think it's more readable and simple than anything else However, if you have any suggestions on how to make the code simpler, please give me a better suggestion

Solution

So the problem here is that the generic parameter Y used for dynamic conversion is regarded as object It will never throw CCE You threw a CCE in the calling method because you have broken static type security

X makes no sense here:

It is almost certain that the right solution is not to try such a thing It's terrible The spell casting is terrible

However, if you decide to write nonsense, you can pass the class object:

public static <T> T evilMethod(Class<T> clazz,Object obj) {
    try {
        return clazz.cast(obj);
    } catch (ClassCastException exc) {
        return null;
    }
}