Consider the following pseudo-Java: Object foo = ... if (foo instanceof String) { System.out.println(foo.toLowerCase()) } The above is not

Consider the following pseudo-Java: Object foo = ... if (foo instanceof String) { System.out.println(foo.toLowerCase()) } The above is not valid Java, because foo has type Object, which does not have a toLowerCase() method, so the compiler refuses to compile it. What you need to do is something like: Object foo = ... if (foo instanceof String) { String sfoo = (String) foo System.out.println(sfoo.toLowerCase()) } Granted, you don't necessarily need to explicitly redefine in, as Java allows anonymous casting: Object foo = ... if (foo instanceof String) { System.out.println(((String) foo).toLowerCase()) } Regardless, the point still stands. Java (and most strongly typed languages with an inheritance based type system) requires an explicit cast, even if a straight forward static analysis would show that the object in question is already the desired type.