(String) or .toString()?

Question

I have a method with an Object o parameter.

In this method, I exactly know there is a String in \"o\" which is not null. There is no need t

Answer 1

If you know the Object o is a String, I'd say just cast it to a String and enforce it that way. Calling toString() on an object that you know for sure is a String might just add confusion.

If Object o might be anything other than a String, you'll need to call toString().

Answer 2

Given that the reference type is an Object and all Objects have a toString() just call object.toString(). String.toString() just returns this.

• toString() is less code to type.
• toString() is less bytecode.
• casting is an expensive operation VS a polymorphic call.
• the cast could fail.
• Use String.valueOf( object ) which just calls object.toString() if its not null.

Answer 3

I would use a cast. That validates your "knowledge" that it's a string. If for whatever reason you end up with a bug and someone passes in something other than a string, I think it would be better to throw an exception (which a cast will do) than continue to execute with flawed data.