instanceof: incompatible conditional operand types A and B

Some Guy: A related issue that I have come across recently (and which led me to this page, before I figured out what was going on) is that the Eclipse environment can report "Incompatible conditional operand types" in an 'instanceof' expression erroneously due to a missing 'import' statement for the type on the right of the 'instanceof'. I spent a while trying to figure out how the types in question could possibly be incompatible before figuring out that a missing import was causing the whole problem. Hopefully this information saves somebody some time.

 

在同一个类加载器加载的前提下，使用其生成的对象，去比较才有意义。不同的类加载器加载的类生成对象，互相instanceof返回false。

 

instanceof keyword is a binary operator used to test if an object (instance) is a subtype of a given Type.

 

And,

dog instanceof Cat // does not even compile!

This is because Dog is neither a subtype nor a supertype of Cat, and it also does not implement it.