Instanceof

Question 1

The left operand of instanceof MUST…

Answer 1

be a reference variable and not a primitive.

Question 2

Right operand of instanceof MUST be…

Answer 2

a reference type name, i.e., a class, an interface, or an enum name.

Question 3

Can two wrappers of different types (for example, an Integer and a Short) be compared using ==?

Answer 3

Two wrappers of different types (for example, an Integer and a Short) cannot be compared using ==. This will lead to a compilation fail.

Question 4

Can an int with or any other numeric primitive b e compared with other numeric wrappers (like a Short or a Double)?

Answer 4

Any two numeric primitives can be compared using == operator.
Even a numeric primitive and a primitive wrapper (for example, an int with a Short or a Double) can be compared.

Question 5

Will this code compile ?

Short k = 9; Integer i = 9; System.out.println(k == i);

Answer 5

This will not compile because k and i are referring to objects that have no IS-A relationship among themselves.